Heterocyclic thioamide derivatives

ABSTRACT

It has been discovered that compounds of the formula:                    
     and the pharmaceutically acceptable salts and esters thereof wherein X and Y are as defined below, inhibit the binding of VCAM-1 to VLA-4 and are usefull in treating inflammation associated with chronic inflammatory diseases such as rheumatoid arthritis (RA), multiple sclerosis, (MS), asthma, and inflammatory bowel disease (IBD).

This application claims priority under 35 U.S.C. § 119(e) of provisionalapplication Ser. No. 60/120,475, filed Feb. 18, 1999. This is adivisional of copending application Ser. No. 09/505,903 filed Feb. 17,2000.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to:

Chen, et al. U.S. Ser. No. 09/138,353 filed Aug. 21, 1998,

Title: N-ALKANOYLPHENYLALANINE DERIVATIVES; and

Chen, et al. U.S. Ser. No. 09/137,798 filed Aug. 21, 1998,

Title: N-AROYLPHENYLALANINE DERIVATIVES.

BACKGROUND OF THE INVENTION

Vascular cell adhesion molecule-1 (VCAM-1), a member of theimmunoglobulin (Ig) supergene family, is expressed on activated, but notresting, endothelium. The integrin VLA-4 (a₄b₁), which is expressed onmany cell types including circulating lymphocytes, eosinophils,basophils, and monocytes, but not neutrophils, is the principal receptorfor VCAM-1. Antibodies to VCAM-1 or VLA-4 can block the adhesion ofthese mononuclear leukocytes, as well as melanoma cells, to activatedendothelium in vitro. Antibodies to either protein have been effectiveat inhibiting leukocyte infiltration and preventing tissue damage inseveral animal models of inflammation. Anti-VLA-4 monoclonal antibodieshave been shown to block T-cell emigration in adjuvant-inducedarthritis, prevent eosinophil accumulation and bronchoconstriction inmodels of asthma, and reduce paralysis and inhibit monocyte andlymphocyte infiltration in experimental autoimmune encephalitis (EAE).Anti-VCAM-1 monoclonal antibodies have been shown to prolong thesurvival time of cardiac allografts. Recent studies have demonstratedthat anti-VLA-4 mAbs can prevent insulitis and diabetes in non-obesediabetic mice, and significantly attenuate inflammation in thecotton-top tamarin model of colitis.

Thus, compounds which inhibit the interaction between α₄-containingintegrins and VCAM-1 will be useful as therapeutic agents for thetreatment of inflammation resulting from chronic inflammatory diseasessuch as rheumatoid arthritis, multiple sclerosis (MS), asthma, andinflammatory bowel disease (IBD).

SUMMARY OF THE INVENTION

It has been discovered that compounds of the formula:

and the pharmaceutically acceptable salts and esters thereof wherein Xand Y are as defined below, inhibit the binding of VCAM-1 to VLA-4 andare useful in treating inflammation associated with chronicinflammatorydiseases such as rheumatoid arthritis (RA), multiple sclerosis, (MS),asthma, and inflammatory bowel disease (IBD).

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to the discovery that compounds of theformula:

and the pharmaceutically acceptable salts and esters thereof, inhibitthe binding of VCAM-1 to VLA-4 and are useful in treating inflammationassociated with chronic inflammatory diseases such as rheumatoidarthritis (RA), multiple sclerosis, (MS), asthma, and inflammatory boweldisease (IBD).

In accordance with the invention, X is a group X-1, X-2 or X-3 asdescribed below. Y is a group Y-1, Y-2 or Y-3 as described below.

The group X-1 is of the formula:

wherein:

R₁₅ is halogen, nitro, lower alkyl sulfonyl, cyano, lower alkyl, loweralkoxy, lower alkoxycarbonyl, carboxy, lower alkyl aminosulfonyl,perfluorolower alkyl, lower alkylthio, hydroxy lower alkyl, alkoxy loweralkyl, lower alkylthio lower alkyl, lower alkylsulfinyl lower alkyl,lower alkylsulfonyl lower alkyl, lower alkylsulfinyl, lower alkanoyl,aroyl, aryl, aryloxy;

R₁₆ is hydrogen, halogen, nitro, cyano, lower alkyl, OH, perfluoroloweralkyl, or lower alkylthio.

The groups R₁₅ and R₁₆ are preferably independently hydrogen, loweralkyl, nitro, halogen (especially chloro or fluoro), perfluoromethyl, orcyano for R₁₆, and lower alkyl, nitro, halogen (especially chloro orfluoro), perfluoromethyl, or cyano for R₁₅.

It is preferred that groups selected as R₁₅, or R₁₅ and R₁₆, beelectron-deficient as defined below.

X-2 is a group of the formula:

wherein Het is a 5- or 6-membered heteroaromatic ring containing 1, 2 or3 heteroatoms selected from N, O, and S, or

Het is a 9- or 10-membered bicyclic heteroaromatic ring containing 1, 2,3 or 4 heteroatoms selected from O, S, and N;

R₁₅ and R₁₆ are as above, and

R₃₀ is hydrogen or lower alkyl; and p is an integer from 0 to 1.

Het is preferably a 5- or 6-membered monocyclic heteroaromatic ringcontaining 1, 2 or 3 nitrogens, or a nitrogen and a sulfur, or anitrogen and an oxygen. When Het is a bicyclic heteroaromatic ring, itpreferably contains from 1 to 3 nitrogens as the heteroatoms. R₁₅ ispreferably, nitro, lower alkyl sulfonyl, cyano, lower alkyl, loweralkoxy, perfluorolower alkyl, lower alkylthio, lower alkanoyl, or aryl(especially unsubstituted phenyl); R₁₆ is preferably hydrogen, halogen,nitro, cyano, lower alkyl, perfluoro lower alkyl; and R₃₀, when present,is preferably hydrogen or lower alkyl.

The group X-3 is of the formula:

wherein:

R₁₈ is aryl, heteroaryl,

R₁₉ is substituted or unsubstituted lower alkyl, aryl, heteroaryl,arylalkyl, heteroaryl alkyl, and

R₂₀ is substituted or unsubstituted lower alkanoyl or aroyl

R₁₈ is preferably phenyl. R₁₉ is preferably lower alkyl, which isunsubstituted or substituted by pyridyl or phenyl. R₂₀ is preferablylower alkanoyl

Y is a group of formula Y-1, Y-2, or Y-3 wherein:

Y-1 is a group of the formula:

wherein:

R₂₂ and R₂₃ are independently hydrogen, lower alkyl, lower alkoxy,cycloalkyl, aryl, arylalkyl, nitro, cyano, lower alkylthio, loweralkylsulfinyl, lower alkyl sulfonyl, lower alkanoyl, halogen, orperfluorolower alkyl and at least one of R₂₂ and R₂₃ is other thanhydrogen, and

R₂₄ is hydrogen, lower alkyl, lower alkoxy, aryl, nitro, cyano, loweralkyl sulfonyl, or halogen

Y-2 is a group of the formula

Het is a five or six membered heteroaromatic ring bonded via a carbonatom wherein said ring contains one, two or three heteroatoms selectedfrom the group consisting of N, O and S and R₃₀ and R₃₁ areindependently hydrogen, lower alkyl, cycloalkyl, halogen, cyano,perfluoroalkyl, or aryl and at least one of R₃₀ and R₃₁ is adjacent tothe point of attachment, p is an integer of from 0 to 1.

Y-3 is a 3-7 membered ring of the formula:

wherein:

R₂₅ is lower alkyl, unsubstituted or fluorine substituted lower alkenyl,or a group of formula R₂₆—(CH₂)_(e)—, R₂₆ is aryl, heteroaryl, azido,cyano, hydroxy, lower alkoxy, lower alkoxycarbonyl, lower alkanoyl,lower alkylthio , lower alkyl sulfonyl, lower alkyl sulfinyl, perfluorolower alkanoyl, nitro, or R₂₆ is a group of formula —NR₂₈R₂₉,

wherein

R₂₈ is H or lower alkyl,

R₂₉ is hydrogen, lower alkyl, lower alkoxycarbonyl, lower alkanoyl,aroyl, perfluoro lower alkanoylamino, lower alkyl sulfonyl, loweralkylaminocarbonyl, arylaminocarbonyl,

 or

R₂₈ and R₂₉ taken together form a 4, 5 or 6-membered saturatedcarbocyclic ring optionally containing one heteroatom selected from O,S, and N with the carbon atoms in the ring being unsubstituted orsubstituted by lower alkyl or halogen,

Q is —(CH₂)_(f)O—, —(CH₂)_(f)S—, —(CH₂)_(f)N(R₂₇)—, or —(CH₂)_(f)—,

R₂₇ is H, lower alkyl, aryl, lower alkanoyl, aroyl or loweralkoxycarbonyl,

e is an integer from 0 to 4, and f is an integer from 0 to 3; the dottedbond is optionally hydrogenated.

This invention is directed to a compound of the formula:

wherein X is a group of the formula

wherein:

R₁₅ is halogen, nitro, lower alkyl sulfonyl, cyano, lower alkyl, loweralkoxy, lower alkoxycarbonyl, carboxy, lower alkyl aminosulfonyl,perfluorolower alkyl, lower alkylthio, hydroxy lower alkyl, alkoxy loweralkyl, lower alkylthio lower alkyl, lower alkylsulfinyl lower alkyl,lower alkylsulfonyl lower alkyl, lower alkylsulfinyl, lower alkanoyl,aroyl, aryl, aryloxy;

R₁₆ is hydrogen, halogen, nitro, cyano, lower alkyl, OH, perfluoroloweralkyl, or lower alkylthio; or

X is a group of formula X-2

wherein

Het is a 5- or 6-membered heteroaromatic ring containing 1, 2 or 3heteroatoms selected from N, O, and S, or

Het is a 9- or 10-membered bicyclic heteroaromatic ring containing 1, 2,3 or 4 heteroatoms selected from O, S, and N;

R₁₅ and R₁₆ are as above;

R₃₀ is hydrogen or lower alkyl; and p is an integer from 0 to 1

or X is a group of formula X-3

wherein:

R₁₈ is aryl, heteroaryl, aryl lower alkyl, heteroaryl lower alkyl

R₁₉ is substituted or unsubstituted lower alkyl, aryl, heteroaryl,arylalkyl, heteroaryl alkyl, and

R₂₀ is substituted or unsubstituted lower alkanoyl or aroyl;

and Y is a group of formula Y-1

wherein:

R₂₂ and R₂₃ are independently hydrogen, lower alkyl, lower alkoxy,cycloalkyl, aryl, arylalkyl, nitro, cyano, lower alkylthio, loweralkylsulfinyl, lower alkyl sulfonyl, lower alkanoyl, halogen, orperfluorolower alkyl and at least one of R₂₂ and R₂₃ is other thanhydrogen, and

R₂₄ is hydrogen, lower alkyl, lower alkoxy, aryl, nitro, cyano, loweralkyl sulfonyl, or halogen;

or Y-2 is a group of the formula:

Het is a five or six membered heteroaromatic ring bonded via a carbonatom wherein said ring contains one, two or three heteroatoms selectedfrom the group consisting of N, O and S and R₃₀ and R₃₁, areindependently hydrogen, lower alkyl, cycloalkyl, halogen, cyano,perfluoroalkyl, or aryl and at least one of R₃₀ and R₃₁ is adjacent tothe point of attachment; p is an integer of from 0 to 1;

or Y is a group of formula Y-3

wherein:

R₂₅ is lower alkyl, unsubstituted or fluorine substituted lower alkenyl,or a group of formula R₂₆—(CH₂)_(e)—, R₂₆ is aryl, heteroaryl, azido,cyano, hydroxy, lower alkoxy, lower alkoxycarbonyl, lower alkanoyl,lower alkylthio, lower alkyl sulfonyl, lower alkyl sulfinyl, perfluorolower alkanoyl, nitro, or R₂₆ is a group of formula —NR₂₈R₂₉,

wherein

R₂₈ is H or lower alkyl,

R₂₉ is hydrogen, lower alkyl, lower alkoxycarbonyl, lower alkanoyl,aroyl, perfluoro lower alkanoylamino, lower alkyl sulfonyl, loweralkylaminocarbonyl, arylaminocarbonyl, or R₂₈ and R₂₉ taken togetherform a 4, 5 or 6-membered saturated carbacyclic ring optionallycontaining one heteroatom selected from O, S, and N; with the carbonatoms in the ring being unsubstituted or substituted by lower alkyl orhalogen,

Q is —(CH₂)_(f)O—, —(CH₂)_(f)S—, —(CH₂)_(f)N(R₂₇)—, or —(CH₂)_(f)—,

R₂₇ is H, lower alkyl, aryl, lower alkanoyl, aroyl or loweralkoxycarbonyl,

e is an integer from 0 to 4, and

f is an integer from 0 to 3; and the dotted bond is optionallyhydrogenated;

and pharmaceutically acceptable salts and esters thereof.

Preferred compounds are as follows:

Compounds where X is a group of the formula

and Y, R₁₅ and R₁₆ are as in formula 1.

Such compounds where R₁₅ is lower alkyl, nitro, halogen,perfluoromethyl, or cyano and R₁₆ is hydrogen, lower alkyl, nitro,halogen, perfluoromethyl, or cyano, especially where R₁₅ and R₁₆ areindependently chloro or fluoro are preferred, especially where X-1 isselected from the group of

Compounds of formula 1 wherein X is a group of the formula X-2

and p, Y, R₁₅, R₁₆, and R₃₀ are as in formula 1 (compound A) especiallywhere Het is a 5- or 6-membered monocyclic heteroaromatic ringcontaining 1, 2 or 3 nitrogens, or a nitrogen and a sulfur, or anitrogen and an oxygen or where Het is a bicyclic heteroaromatic ringcontaining from 1 to 3 nitrogens or where R₁₅ is nitro, lower alkylsulfonyl, cyano, lower alkyl, lower alkoxy, perfluorolower alkyl, loweralkylthio, lower alkanoyl, or aryl, especially where aryl isunsubstituted phenyl. In compound A R₁₆ may be hydrogen, halogen, nitro,cyano, lower alkyl, perfluoro lower alkyl; and R₃₀ is hydrogen or loweralkyl, or in compound A Het may be a 6 membered monocyclicheteroaromatic ring containing 1 or 2 nitrogens or a 10 memberedbicyclic heteroaromatic ring containing one nitrogen, R₁₅ is loweralkyl, or perfluoroalkyl and R₁₆ is hydrogen, lower alkyl, orperfluoroalkyl, and R₃₀ is absent. In compound A, X-2 may be selectedfrom the group of

Compounds of formula 1 wherein X is a group of formula X-3

and Y, R₁₈, R₁₉, and R₂₀ are as in formula 1 (compound B). In compoundB, it is preferred that R₁₈ is phenyl. In compound B it is alsopreferred that R₁₉ is lower alkyl which is unsubstituted or substitutedby pyridyl or phenyl. In compound B it is also preferred that R₂₀ issubstituted or unsubsituted lower alkanoyl. In compound B it is alsopreferred that R₁₈ is phenyl, R₁₉ is lower alkyl which is unsubstitutedor substituted by pyridyl or phenyl and R₂₀ is lower alkanoyl. Incompound B it is preferred that R₁₈ is phenyl which is unsubstituted orsubstituted by halogen or lower alkoxy; R₁₉ is phenyl lower alkyl whichis unsubstituted or substituted by lower alkoxy, pyridyl lower alkyl, orlower alkyl; and R₂₀ is substituted or unsubstituted lower alkanoyl.

In this latter compound, it is preferred that X-3 is selected from thegroup of

Compounds of formula 1 where Y is a group of formula

and X, R₂₂, R₂₃, and R₂₄ are as in formula 1 (compound C). It ispreferred for compound C that R₂₂ and R₂₃ are lower alkyl,trifluoromethyl, or halogen and R₂₄ is hydrogen, lower alkyl, loweralkoxy, or halogen, especially when Y-1 is selected from the group of

Compounds of formula 1 wherein Y is a group of the formula Y-2

and p, X, Het, R₃₀ and R₃₁, are as in formula 1 (compound D). It ispreferred for compound D that Het is a 6 membered heteroaromatic ring,especially where the heteroatom is N, and preferably where Y-2 isselected from the group of

Compounds of formula 1 where Y is a group of formula Y-3

and Y, R₂₅ and Q are as in formula 1, and the dotted bond can beoptionally hydrogenated (compound E). It is preferred for compound Ethat Y-3 is selected from the group of

A compound of formula 1 wherein X is a group of the formula X-1 and Y isa group of the formula Y-1.

A compound of formula 1 wherein X is a group of the formula X-1 and Y isa group of the

formula Y-2.

A compound of formula 1 wherein X is a group of the formula X-1 Y is agroup of the formula Y-3 wherein R₁₅, R₁₆, R₂₅ and Q are as above; andthe dotted bond can be optionally hydrogenated.

A compound of formula 1 wherein X is a group of the formula X-2 and Y isa group of the formula Y-1.

A compound of formula 1 wherein X is a group of the formula X-2 and Y isa group of the formula Y-2.

A compound of formula 1 wherein X is a group of the formula X-2 and Y isa group of the

formula Y-3 wherein R₁₅, R₁₆, R₂₅, R₃₀, Q and p are as above and thedotted bond can be optionally hydrogenated.

A compound of formula 1 where X is a group of the formula X-3 and Y is agroup of the formula Y-1.

A compound of formula 1 wherein X is a group of the formula X-3 and Y isa group of the formula Y-2.

A compound of formula 1 wherein X is a group of the formula X-3 and Y isa group of the formula Y-3 where R₁₈, R₁₉, R₂₀, R₂₅, and Q are as aboveand the dotted bond can be optionally hydrogenated.

A compound of claim 1 wherein X is a group of the formula X-1

wherein R₁₆ is in the ortho position and is hydrogen, lower alkyl,nitro, cyano, halogen, lower alkylthio, perfluoroloweralkyl and R₁₅ islower alkyl, nitro, cyano, halogen, lower alkylsulfonyl,perfluoroloweralkyl, and Y is a group of the formula Y-1

where R₂₂ is hydrogen, halogen, trifluoroalkyl, or lower alkyl and R₂₃is halogen, trifluoroalkyl, or lower alkyl, and R₂₄ is hydrogen or Y isa group of the formula Y-3

wherein Q is as above and the dotted bond can be optionallyhydrogenated; R₂₅ is R₂₆—(CH₂)_(e)—; e is 2-4 and R₂₆ is azido, cyano,hydroxy, lower alkoxy, lower alkoxycarbonyl, lower alkanoyl, lower alkylsulfonyl, lower alkyl sulfinyl, perfluoro lower alkanoyl, nitro, orlower alkylthio or R₂₅ is NHR₂₉ where R₂₉ is lower alkanoyl or loweralkylamino carbonyl (compound E).

In compound B it is preferred that X is a group of the formula X-1

wherein R₁₆ is i n the ortho position and is hydrogen, lower alkyl,nitro, cyano, halogen , lower alkylio, perfluoroloweralkyl and R₁₅ islower alkyl, nitro, cyano, halogen, lower alkylsulfonyl,perfluorolowerauknl; and Y is a group of the formula Y-1

where R₂₂ is hydrogen, halogen, or lower alkyl and R₂₃ is halogen orlower alkyl, and R₂₄ is hydrogen, especially where R₁₆ is hydrogen orhalogen and R₁₅ is halogen; R₂₂ is hydrogen, halogen, ethyl, or methyland R₂₃ is halogen, ethyl, or methyl, and additionally where R₁₆ is inthe ortho position and R₁₅ and R₁₆ are both chlorine, and R₂₂ is methyland R₂₃ is chlorine or ethyl. An example of such a compound is4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[(2-chloro-6-methylphenyl)thioxomethyl]-L-phenylalanine.

In compound E it is also preferred that X is a group of the formula X-1

wherein R₁₆ is in the ortho position and is hydrogen, lower alkyl,nitro, cyano, halogen, lower alkylthio, perfluoroloweralkyl and R₁₅ islower alkyl, nitro, cyano, halogen, lower alkylsulfonyl,perfluoroloweralkyl; and Y is a group of the formula Y-3

which is a four to six membered cycloalkyl ring, R₂₅ is R₂₆—(CH₂)_(e)—;e is 2-4 and R₂₆ is azido, cyano, hydroxy, lower alkoxy, loweralkoxycarbonyl, lower alkanoyl, lower alkyl sulfonyl, lower alkylsulfinyl, perfluoro lower alkanoyl, nitro, or lower alkylthio; and thedotted bond is hydrogenated. In such a compound it is preferred that R₁₆is hydrogen or halogen and R₁₅ is halogen; and Y-3 is a four or fivemembered ring and R₂₆ is lower alkoxy, lower alkyl sulfonyl, lower alkylsulfinyl, or lower alkylthio, especially where R₁₆ is in the orthoposition and R₁₅ and R₁₆ are both chlorine, and R₂₆ is lower alkylsulfonyl or lower alkylthio. An example of such a compound is4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[1-[(4-methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalanine.

For another preferred compound E X is a group of the formula X-1

where R₁₆ is hydrogen or halogen and R₁₅ is halogen and Y is a group ofthe formula Y-1

where R₂₂ is hydrogen, halogen, ethyl, or methyl and R₂₃ is halogen,ethyl, or methyl and R₂₄ is hydrogen or Y is a group of the formula Y-3

where Y-3 is a four or five membered ring, R₂₅ is as in claim 39 and R₂₆is lower alkoxy, lower alkyl sulfonyl, lower alkyl sulfinyl, or loweralkylthio, and the dotted bond is optionally hydrogenated. For such acompound it is preferred that R₁₆ is in the ortho position and R₁₅ andR₁₆ are both chlorine, and when Y is Y-1 then R₂₂ is methyl and R₂₃ ischlorine or ethyl and when Y is Y-3, Y-3 is a four or five membered ringand R₂₆ is lower alkyl sulfonyl or lower alkylthio.

A compound of formula 1 wherein Y is as in formula 1 and X is X-1

where R₁₅ is ortho and is halogen, lower alkyl, or perfluoroalkyl andR₁₆ is hydrogen, halogen, lower alkyl, or perfluoroalkyl (compound F).

For compound F it is preferred that R₁₅ is chlorine and R₁₆ is hydrogenor chlorine.

A compound of formula 1 wherein Y is as in formula 1 and X is X-2 whereHet is pyridine or pyrimidine and R₁₅ is lower alkyl or perfluoroalkylR₁₆, and R₂₀ are hydrogen, lower alkyl, or perfluoroalkyl (compound G).

A compound of formula 1 wherein Y is as in formula 1 and X is X-3 whereR₁₉ is pyridinyl lower alkyl or phenyl lower alkyl, R₂₀ is loweralkanoyl, and R₁₈ is phenyl (compound H).

A compound of formula 1 where X is as in formula 1 and Y is Y-1 whereR₂₂ is hydrogen or lower alkyl, R₂₃ is halogen, lower alkyl, orperfluoroalkyl, and R₂₄ is hydrogen, especially where R₂₂ is hydrogen ormethyl and R₂₃ is halogen, ethyl, or trifluoromethyl.

A compound of formula 1 wherein X is as in formula 1 and Y is Y-3 whichis a four to six membered cycloalkyl ring, R₂₅ is R₂₆—(CH₂)_(e)—, e is2-4, and R₂₆ is alkoxy, lower alkyl sulfonyl, loweralkylthio, or NHR₂₉where R₂₉ is loweralkoxycarbonyl or loweralkylaminocarbonyl, and thedotted bond is hydrogenated. It is preferred that R₂₆ is methoxy, methylsulfonyl, or methylthio.

A preferred compound F has Y is Y-1 where R₂₂ is hydrogen or loweralkyl, R₂₃ is halogen, lower alkyl, or perfluoroalkyl, and R₂₄ ishydrogen. It is preferred that R₁₅ is chlorine and R₁₆ is hydrogen orchlorine. Examples are

4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[(2-bromophenyl)thioxomethyl]-L-phenylalanine;

4-[[(2,6,-dichlorophenyl)carbonyl]amino]-N-[(2-ethyl-6-methylphenyl)thioxomethyl]L-phenylalanine.

4-[[(2,6,-dichlorophenyl)carbonyl]amino]-N-[(2-fluorophenyl)thioxomethyl]-L-phenylalanine.

4-[[(2,6,-dichlorophenyl)carbonyl]amino]-N-[[2-(tifluoromethyl)phenyl]thioxomethyl]-L-phenylalanine.

In a preferred compound G, Y is Y-1 where R₂₂ is hydrogen or loweralkyl, R₂₃ is halogen, lower alkyl, or perfluoroalkyl, and R₂₄ ishydrogen.

In a preferred compound H, Y is Y-1 where R₂₂ is hydrogen or loweralkyl, R₂₃ is halogen, lower alkyl, or perfluoroalkyl, and R₂₄ ishydrogen. An example of such a compound is4-[(2S,4R)-3-acetyl-2-phenyl-4-[(3-pyridinyl)methyl]-5-oxo-imidazolidin-1-yl]-N-[(2-ethyl-6-methylphenyl)thioxomethyl]-L-phenylalanine.

In a preferred compound F, Y is Y-3 which is a four to six memberedcycloalkyl ring, R₂₅

is R₂₆—(CH₂)_(e)—, e is 2-4, and R₂₆ is alkoxy, lower alkyl sulfonyl,loweralkylthio, or NHR₂₉ where R₂₉ is loweralkoxycarbonyl orloweralkylaminocarbonyl, and the dotted bond is hydrogenated. It ispreferred that R₁₅ is chlorine and R₁₆ is hydrogen or chlorine. Examplesof such compounds are

4-[[2,6-dichlorophenyl)carbonyl]amino-N-[[1-[2-(acetylamino)ethyl]cyclopentyl]thioxomethyl]-L-phenylalanine.

[[1-[2-[[(methylamino)carbonyl]amino]ethyl]cyclopentyl]thioxomethyl]-4-[[(2,6-dichlorophenyl)carbonyl]amino]L-phenylalanine.

4-[[(2,6,-dichlorophenyl)carbonyl]amino]-N-[[1-(2-methoxyethyl)cyclopentyl]thioxomethyl]-L-phenylalanine.

4-[[(2,6,-dichlorophenyl)carbonyl]amino]-N-[[1-[(4-methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalanine.

4-[[(2,6,-dichlorophenyl)carbonyl]amino]-N-[[1-(3-methylthio)propyl]cyclobutyl]thioxomethyl]-L-phenylalanine.

4-[[(2,6,-dichlorophenyl)carbonyl]amino]-N-[[1-(3-methylsulfonyl)propyl]cyclobutyl]thioxomethyl]-L-phenylalanine.

It is preferred that R₂₆ is methoxy, methyl sulfonyl, or methyl thio,especially where R₁₅ is chlorine and R₁₆ is hydrogen or chlorine.

A preferred compound G wherein Y is Y-3 which is a four to six memberedcycloalkyl ring, R₂₅ is R₂₆(CH₂)_(e)—, e is 2-4, and R₂₆ is alkoxy,lower alkyl sulfonyl, loweralkylthio, or NHR₂₉ where R₂₉ isloweralkoxycarbonyl or loweralkylaminocarbonyl, and the dotted bond ishydrogenated. Preferably R₂₆ is methoxy, methyl sulfonyl, or methylthio. Examples are

4-[(2,6-dimethyl-3-pyridinylcarbonyl)amino]-N-[[1-[(4-methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalanine.

4-[[[4-(trifluoromethyl)-5-pyrimidinyl]carbonyl]amino]-N-[[1-(4-methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalanine.

4-[[(2,4-dimethyl-6-trifluoromethyl-3-pyridinyl)carbonyl]amino]-N-[[1-[(4-methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalanine.

In a preferred compound H, Y is Y-3 which is a four to six memberedcycloalkyl ring, R₂₅

is R₂₆(CH₂)_(e)—, e is 2-4, and R₂₆ is alkoxy, lower alkyl sulfonyl,loweralkylthio, or NHR₂₉ where R₂₉ is loweralkoxycarbonyl orloweralkylaminocarbonyl, and the dotted bond is optionally hydrogenated,especially where R₂₆ is methoxy, methyl sulfonyl, or methyl thio.Examples are

4-[(2S,4R)-3-acetyl-2-phenyl-4-[(3-phenyl)methyl]-5-oxo-imidazolidin-1-yl]-N-[[(4-methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalanine

4-[(2R,4R)-3-acetyl-2-phenyl-4-[(3-phenyl)methyl]-5-oxo-imidazolidin-1-yl]-N-[[(4-methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalanine.

As used in this specification, the terms are defined as follows:

The term “halogen” means bromine, chlorine, fluorine, or iodine, and theterm “halo” means a halogen substituent.

The term “perfluoro” means complete substitution of all hydrogen atomswith fluoro substituted, as in perfluoro lower alkyl,perfluoroloweralkanoyl and perfluoroalkanoylamino. An example istrifluoromethyl.

The term “lower alkyl”, alone or in combination (for example as part oflower alkanoyl, below), means a straight-chain or branched-chain alkylgroup containing a maximum of six carbon atoms, such as methyl, ethyl,n-propyl, isopropyl, n-butyl, sec.butyl, isobutyl, tert.butyl, n-pentyl,n-hexyl and the like. Lower alkyl groups may be unsubstituted orsubstituted by one or more groups selected independently fromcycloalkyl, nitro, aryloxy, aryl (preferably phenyl or pyridyl), hydroxy(lower alkylhydroxy or hydroxylower alkyl), halogen, cyano, lower alkoxy(alkoxy lower alkyl or lower alkyl alkoxy), lower alkanoyl, loweralkylthio (lower alkylthio lower alkyl) sulfinyl (lower alkyl sulfinyl),sulfinyl lower alkyl (lower alkyl sulfinyl lower alkyl) sulfonyl (loweralkyl sulfonyl), sulfonyl lower alkyl (lower alkyl sulfonyl lower alkyl)perfluoro (perfluoro lower alkyl) and substituted amino such asaminosulfonyl (lower alkyl aminosulfonyl) or aminocarbonyl (lower alkylaminocarbonyl). Examples of substituted lower alkyl groups include2-hydroxylethyl, 3-oxobutyl, cyanomethyl, and 2-nitropropyl. The term“lower alkylthio” means a lower alkyl group bonded through a divalentsulfur atom, for example, a methyl mercapto or a isopropyl mercaptogroup.

The term “cycloalkyl” means an unsubstituted or substituted 3- to7-membered carbacyclic ring. Substituents useful in accordance with thepresent invention are hydroxy, halogen, cyano, lower alkoxy, loweralkanoyl, lower alkyl, aroyl, lower alkylthio, lower alkyl sulfinyl,lower alkyl sulfonyl, aryl, heteroaryl and substituted amino.

The term “lower alkoxy” means a lower alkyl group as defined above,bonded through an oxygen atom. Examples are methoxy, ethoxy, n-propoxy,isopropoxy, n-butoxy, tert-butoxy and the like.

The term “lower alkenyl” means a nonaromatic partially unsaturatedhydrocarbon chain containing at least one double bond, which ispreferably 1-10 and more preferably 1-6 carbons in length. The group maybe unsubstituted, or substituted with conventional substituents,preferably fluoro. Examples are vinyl, allyl, dimethylallyl, butenyl,isobutenyl, pentenyl.

The term “aryl” means a mono- or bicylic aromatic group, such as phenylor naphthyl, which is unsubstituted or substituted by conventionalsubstituent groups. Preferred substituents are lower alkyl, loweralkoxy, hydroxy lower alkyl, hydroxy, hydroxyalkoxy, halogen, loweralkylthio, lower alkylsulfinyl, lower alkylsulfonyl, cyano, nitro,perfluoroalkyl, alkanoyl, aroyl, aryl alkynyl, lower alkynyl,aminoalkylcarbonyl (arylaminocarbonyl) and lower alkanoylamino. Theespecially preferred substituents are lower alkyl, hydroxy, andperfluoro lower alkyl. Examples of aryl groups that may be used inaccordance with this invention are phenyl, p-tolyl, p-methoxyphenyl,p-chlorophenyl, m-hydroxy phenyl, m-methylthiophenyl,2-methyl-5-nitrophenyl, 2,6-dichlorophenyl, 1-naphthyl and the like.

The term “arylalkyl” means a lower alkyl group as hereinbefore definedin which one or more hydrogen atoms is/are replaced by an aryl group asherein defined. Any conventional aralkyl may be used in accordance withthis invention, such as benzyl and the like. Similarly, the term“heteroarylalkyl” is the same as an arylalkyl group except that there isa heteroaryl group as defined below in place of an aryl group. Either ofthese groups may be unsubstituted, or may be substituted on the ringportion with conventional substituents such as

The term “heteroaryl” means an unsubstituted or substituted 5- or6-membered monocyclic hetereoaromatic ring or a 9- or 10-memberedbicyclic hetereoaromatic ring containing 1, 2, 3 or 4 hetereoatoms whichare independently N, S or O. Examples of hetereoaryl rings are pyridine,benzimidazole, indole, imidazole, thiophene, isoquinoline, quinzolineand the like. Substituents as defined above for “aryl” apply equallyhere in the definition of heteroaryl. The term “heteroaromatic ring” maybe used interchangeably with the term heteroaryl.

The term “lower alkoxycarbonyl” means a lower alkoxy group bonded via acarbonyl group. Examples of alkoxycarbonyl groups are ethoxycarbonyl andthe like.

The term “lower alkylcarbonyloxy” means lower alkylcarbonyloxy groupsbonded via an oxygen atom, for example an acetoxy group.

The term “lower alkanoyl” means lower alkyl groups bonded via a carbonylgroup and embraces in the sense of the foregoing definition groups suchas acetyl, propionyl and the like. Lower alkanoyl groups may beunsubstituted, or substituted with conventional substituents such asalkoxy, lower alkyl, hydroxy, aryl, and hetereoaryl.

The term “lower alkylcarbonylamino” means lower alkylcarbonyl groupsbonded via a nitrogen atom, such as acetylamino.

The term “aroyl” means an mono- or bicyclic aryl or heteroaryl groupbonded via a carbonyl group. Examples of aroyl groups are benzoyl,3-cyanobenzoyl, 2-naphthyl and the like. Aroyl groups may beunsubstituted, or substituted with conventional substituents such as

The term “aryloxy” means an aryl group, as hereinbefore defined, whichis bonded via an oxygen atom. The preferred aryloxy group is phenoxy.

The term “electron-deficient substituent” means a substituent on anaromatic or heteroaromatic ring which has a positive Hammett sigma valusas defined for example in Jerry March, Advanced Organic Chemistry,2^(nd) Edition, McGraw Hill, 1977, page 246-253. Typical electronwithdrawing groups are cyano, nitro, chloro, alkoxycarbonyl lower alkylsulfonyl, and aminocarbonyl.

In the compound of formula 1, Y is preferably the group Y-1 whereby theinvention comprises a compound of the formula:

wherein X, R₂₂, R₂₃ and R₂₄ are as above.

In the group Y-1, R₂₂ and R₂₃ are preferably lower alkyl or halogen andR₂₄ is preferably hydrogen.

Among the groups Y-1, when R₂₃ is lower-alkyl or halogen, Y-1 ispreferably:

When Y is a group Y-2, Y is preferably:

When Y is a group Y-3, Y is preferably:

The especially preferred groups X-1 are of the formula:

The especially preferred groups X-2 are of the formula:

The especially preferred groups X-3 are of the formula:

The compounds of the invention can exist as stereoisomers anddiastereomers, all of which are encompassed within the scope of thepresent invention.

The compounds of the invention inhibit the binding of VCAM-1 andfibronectin to VLA-4 on circulating lymphocytes, eosinophils, basophils,and monocytes (“VLA-4-expressing cells”). The binding of VCAM-1 andfibronectin to VLA-4 on such cells is known to be implicated in certaindisease states, such as rheumatoid arthritis, multiple sclerosis,inflammatory bowel disease, and particularly in the binding ofeosinophils to pulmonary endothelium which contributes to the cause ofthe pulmonary inflammation which occurs in asthma. Thus, the compoundsof the present invention would be useful for the treatment of asthma.

On the basis of their capability of inhibiting binding of VCAM-1 andfibronectin to VLA-4 on circulating lymphocytes, eosinophils, basophils,and monocytes, the compounds of the invention can be used as medicamentfor the treatment of disorders which are known to be associated withsuch binding. Examples of such disorders are rheumatoid arthritis,multiple sclerosis, asthma, and inflammatory bowel disease. Thecompounds of the invention are preferably used in the treatment ofdiseases which involve pulmonary inflammation, such as asthma. Thepulmonary inflammation, which occurs in asthma, is related to eosinophilinfiltration into the lungs wherein the eosinophils bind to endotheliumwhich has been activated by some asthma-triggering event or substance.

Furthermore, compounds of the invention also inhibit the binding ofVCAM-1 and MadCAM to the cellular receptor alpha4-beta7, also known asLPAM, which is expressed on lymphocytes, eosinophils and T-cells. Whilethe precise role of alpha4-beta7 interaction with various ligands ininflammatory conditions such as asthma is not completely understood,compounds of the invention which inhibit both alpha4-beta1 andalpha4-beta7 receptor binding are particularly effective in animalmodels of asthma. Furthermore work with monoclonal antibodies toalpha4-beta7 indicate that compounds which inhibit alpha4-beta7 bindingto MadCAM or VCAM are useful for the treatment of inflammatory boweldisease. They would also be useful in the treatment of other diseases inwhich such binding is implicated as a cause of disease damage orsymptoms.

The compounds of the invention can be administered orally, rectally, orparentally, e.g., intravenously, intramuscularly, subcutaneously,intrathecally or transdermally; or sublingually, or as opthalmalogicalpreparations, or as an aerosol in the case of pulmonary inflammation.Capsules, tablets, suspensions or solutions for oral administration,suppositories, injection solutions, eye drops, salves or spray solutionsare examples of administration forms.

Intravenous, intramuscular, oral or inhalation administration is apreferred form of use. The dosages in which the compounds of theinvention are administered in effective amounts depending on the natureof the specific active ingredient, the age and the requirements of thepatient and the mode of administration. Dosages may be determined by anyconventional means, e.g., by dose-limiting clinical trials. Thus, theinvention further comprises a method of treating a host suffering from adisease in which VCAM-1 of fibronectin binding to VLA-4-expressing cellsis a causative factor in the disease symptoms or damage by administeringan amount of a compound of the invention sufficient to inhibit VCAM-1 orfibronectin binding to VLA-4-expressing cells so that said symptoms orsaid damage is reduced. In general, dosages of about 0.1-100 mg/kg bodyweight per day are preferred, with dosages of 1-25 mg/kg per day beingparticularly preferred, and dosages of 1-10 mg/kg body weight per daybeing especially preferred.

The invention further comprises pharmaceutical compositions whichcontain a pharmaceutically effective amount of a compound of theinvention and a pharmaceutically acceptable carrier. Such compositionsmay be formulated by any conventional means. Tablets or granulates cancontain a series of binders, fillers, carriers or diluents. Liquidcompositions can be, for example, in the form of a sterilewater-miscible solution. Capsules can contain a filler or thickener inaddition to the active ingredient. Furthermore, flavor-improvingadditives as well as substances usually used as preserving, stabilizing,moisture-retaining and emulsifying agents as well as salts for varyingthe osmotic pressure, buffers and other additives can also be present.

The previously mentioned carrier materials and diluents can comprise anyconventional pharmaceutically acceptable organic or inorganicsubstances, e.g., water, gelatin, lactose, starch, magnesium stearate,talc, gum arabic, polyalkylene glycols and the like.

Oral unit dosage forms, such as tablets and capsules, preferably containfrom 25 mg to 1000 mg of a compound of the invention.

The compounds of the present invention may be prepared by anyconventional means. In reaction Scheme 1, a 4-nitro-L-phenylalaninederivative of formula 1 in which R₁ is lower alkyl, which is a knowncompound or readily prepared by conventional means, is acylated with abenzoic acid derivative of formula 2 in which R₂ hydrogen, lower alkyl,lower alkoxy, cycloalkyl, aryl, arylalkyl, nitro, cyano, loweralkylthio, lower alkylsulfinyl, lower alkyl sulfonyl, lower alkanoyl,halogen, or perfluorolower alkyl, R₃ is hydrogen, halogen or lower alkyland R₄ is hydrogen, lower alkyl, lower alkoxy, aryl, nitro, cyano, loweralkyl sulfonyl, or halogen, using conventional means for amide bondformation. For example, a compound of formula 2 may be converted to thecorresponding acid chloride and condensed with a compound of formula 1in the presence of a proton acceptor such as a tertiary alkylamine.Alternatively compound 1 can be coupled with a carboxylic acid offormula 2 using standard peptide coupling conditions, for example HBTUin the presence of DIPEA in a polar, aprotic solvent such as DMF at atemperature between 0° C. and room temperature to give a compound offormula 3.

Conversion of the compound of formula 3 to the corresponding thioamideof formula 4 can be carried out by treatment with Lawesson's reagentwhich is[2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulfide].The procedure is standard and has been described in detail. See forexample, Scheibey, S., Pedersen, B. S., Lawesson, S.-O. Bull Soc. Chim.Belg. 1978 87, 229 and Cava, M. P., Levinson, M. I., Tetrahedron 1985,41, 5061. The nitro group of the compound of formula 4 may be reduced tothe corresponding amine by any of the conventional means which arecompatible with thioamides. One convenient procedure employs zinc dustas the reducing agent in the presence of methanol, ammonium chloride andwater at a temperature of from 35 to 60° C. to give a compound offormula 5. Acylation of this compound with an aryl- or heteroarylcarboxylic acid of formula 6 using standard peptide coupling conditions,for example HBTU in the presence of DIPEA in a polar, aprotic solventsuch as DMF at a temperature between 0° C. and room temperature gives acompound of formula 7. In certain cases, for example with hinderedcarboxylic acids 6, it may be advantageous to form the correspondingacid halide and react it with the amine of formula 5, typically in thepresence of a slight excess of a base such as a tertiary amine or4-(dimethylamino)pyridine. The carboxylic acid of formula 6 may besubstituted by halogen, nitro, lower alkyl sulfonyl, cyano, lower alkyl,lower alkoxy, lower alkoxycarbonyl, carboxy, lower alkyl aminosulfonyl,perfluorolower alkyl, lower alkylthio, hydroxy lower alkyl, alkoxy loweralkyl, alkylthio lower alkyl, alkylsulfinyl lower alkyl, alkylsufonyllower alkyl, lower alkylsulfinyl, lower alkanoyl, aroyl, aryl, aryloxy.Where appropriate, it may also incorporate suitably protected reactivefunctionalities which must be removed to permit final conversion intocompounds of the invention. The choice and use of such groups will beapparent to those skilled in the art. Guidance for the selection and useof protecting groups is provided in standard reference works, forexample: “T. W. Green and P. G. M. Wuts, Protective Groups in OrganicSynthesis, 2^(nd) edition, Wiley Interscience, New York, 1991. The estermoiety of compound 7 can generally be cleaved to the correspondingcarboxylic acid by treatment with an alkali metal hdyroxide, forexample, lithium hydroxide in aqueous methanol at a temperature of fromroom temperature to 50° C. Depending on the nature of R₁, alternativeprocedures may be preferred. The choice of conditions for ester cleavagein the presence of functionalities such as thioamides is well known tothose skilled in the art.

Ortho-substituted benzoic acid derivatives which are not commerciallyavailable can be prepared by conventional means. For exampleortho-substituted aryl iodides or triflates may be carbonylated in thepresence of carbon monoxide and a suitable palladium catalyst. Thepreparation of such iodide or triflate intermediates is dependent on theparticular substitution pattern desired and they may be obtained bydirect iodination or diazotization of an aniline followed by treatmentwith a source of iodide for example, potassium iodide. Triflates may bederived from the corresponding phenols by conventional means such astreatment with trifluoromethane sulfonic anhydride in the presence of abase such as triethylamine or diisopropylethylamine in an inert solvent.Other means of obtaining ortho-substituted benzoic acids involvestreatment of an 2-methoxyphenyloxazoline derivative such as 9 with analkyl Grignard reagent followed by hydrolysis of the oxazoline ringfollowing the general procedure described by Meyers, A. I., Gabel, R.,Mihelick, E. D, J. Org. Chem. 1978, 43, 1372-1379., to give an acid offormula 10. 2- or 2,6-Disubstituted benzonitriles also serve asconvenient precursors to the corresponsing benzoic acids. In the case ofhighly hindered nitriles, for example 2-chloro-6-methylbenzonitrile,conventional hydrolysis under acidic or basic conditions is difficultand better results are obtained by DIBAL reduction to the correspondingbenzaldehyde followed by oxidation using a sodium chlorite/hydroperoxideoxidizing reagent.

Employing essentially the same procedures described in Scheme 1,utilizing a heteroaromatic carboxylic acid in place of 2, one canprepare compounds of formula 11.

For the synthesis of analogues a branched chain or cycloalkyl moiety, asimilar procedure to that described in scheme 1 can be employed startingwith the appropriate branched chain or cycloalkyl carboxylic acid offormula 12. In this case, R₆ represents is lower alkyl, unsubstituted orfluorine substituted lower alkenyl, or a substituted lower alkyl groupwherein the substituents may be chosen from aryl, heteroaryl, azido,cyano, hydroxy, lower alkoxy, lower alkoxycarbonyl, lower alkylthio,lower alkyl sulfonyl, perfluoro lower alkanoyl, nitro, or a protectedamino group. The amine protecting group must be chosen to be compatiblewith the reagents needed to convert carboxamides to thioamides.Carbamates, for example, the tert-butoxycarbonyl moiety are suitable. Asappropriate, these protecting groups may be removed by conventionalmeans later in the synthesis and the resulting free amine can be furtherfunctionalized utilizing standard methods. For example, the amine can beacylated by treatment with the appropriate anhydride, isocyanate or acidhalide.

The synthesis of imidazolidinones of formula 21 is described in reactionscheme 3. An aminophenylalanine derivative of structure 13 in which R₆is aryl, heteroaryl, branched chain alkyl or derived from a compound offormula 12, and R₇ is lower alkyl, is coupled with a N-protectedalpha-amino acid of formula 14, in which R₈ can be a natural orunnatural, D- or L-α-amino acid side chain and R₉ is a nitrogenprotecting group of the type conventionally used in peptide chemistry,for example, a Fmoc group, using standard peptide coupling conditions,for example HBTU in the presence of DIPEA in a polar, aprotic solventsuch as DMF at a temperature between 0° C. and room temperature to givea compound of formula 15. Depending on the nature of protecting groupR₉, an appropriate deprotection method is employed to give compound offormula 16. In the case of the protecting group R₉ is Fmoc group, it maybe removed from 15 using standard base treatment well known to thosepracticing peptide chemistry, for example with piperidine in DMF, toafford an amine of formula 16. The compound 16 can then react with analdehyde 17, in which R₁₀ is lower alkyl, aryl, or aryl lower alkyl, inthe presence of a water scavenger such as 4Å molecular sieves in anappropriate solvent such as dichloromethane or THF at 25-60° C. to givean imine of formula 18. The imine 18 may then be treated with anacylating agent such as the acyl chloride of formula 19 in which R₁₁ canbe an alkyl or aryl group in the presence of a base such DIPEA or DBU inan appropriate solvent such a as dichloromethane or THF at 25-60° C. togive an acyl imidazolidinone of formula 20. Alternatively, otherreactive acylating groups such as acid anhydrides or mixed anhydridesmay be employed in this reaction. Compound 20 may be converted to acompound of the invention by an appropriate hydrolysis procedure, forexample by hydrolysis by treatment with an alkali metal hydroxide, forexample sodium hydroxide in aqueous alcohol to give, afteracidification, a carboxylic acid of formula 21.

General

Melting points were taken on a Thomas-Hoover apparatus and areuncorrected. Optical rotations were determined with a Perkin-Elmer model241 polarimeter. ¹H-NMR spectra were recorded with Varian XL-200 andUnityplus 400 MHz spectrometers, using tetramethylsilane (TMS) asinternal standard. Electron impact (EI, 70 ev) and fast atom bombardment(FAB) mass spectra were taken on VG Autospec or VG 70E-HF massspectrometers. Silica gel used for column chromatography was MallinkrodtSiliCar 230-400 mesh silica gel for flash chromatography; columns wererun under a 0-5 psi head of nitrogen to assist flow. Thin layerchromatograms were run on glass thin layer plates coated with silica gelas supplied by E. Merck (E. Merck # 1.05719) and were visualized byviewing under 254 nm UV light in a view box, by exposure to I₂ vapor, orby spraying with either phosphomolybdic acid (PMA) in aqueous ethanol,or after exposure to Cl₂, with a 4,4′-tetramethyldiaminodiphenylmethanereagent prepared according to E. Von Arx, M. Faupel and M Brugger, J.Chromatography, 1976, 120, 224-228.

Reversed phase high pressure liquid chromatography (RP-HPLC) was carriedout using either a Waters Delta Prep 4000 employing a 3×30 cm, WatersDelta Pak 15 μM C-18 column at a flow of 40 mL/min employing a gradientof acetonitrile:water (each containing 0.75% TFA) typically from 5 to95% acetonitrile over 35-40 min or a Rainin HPLC employing a 41.4×300mm, 8 μM, Dynamax™ C-18 column at a flow of 49 mL/min and a similargradient of acetonitrile:water as noted above. HPLC conditions aretypically described in the format (5-95-35-214); this refers to a lineargradient of from 5% to 95% acetonitrile in water over 35 min whilemonitoring the effluent with a UV detector set to a wavelength of 214nM.

Methylene chloride (dichioromethane), 2-propanol, DMF, THF, toluene,hexane, ether, and methanol, were Fisher reagent grade and were usedwithout additional purification except as noted, acetonitrile was Fisherhplc grade and was used as is.

Definitions:

THF is tetrahydrofuran,

DMF is N,N-dimethylformamide,

HOBT is 1-hydroxybenzotriazole,

BOP is [(benzotriazole-1-yl)oxy]tris-(dimethylamino)phosphoniumhexafluorophosphate,

HATU is O-(7-azabenzotriazol-1-yl)-1,1,3,3-tetramethyluroniumhexafluorophosphate

HBTU is O-benzotriazole-N,N,N′,N′,-tetramethyluroniumhexafluorophosphate,

DIPEA is diisopropylethylamine,

DMAP is 4-(N,N-dimethylamino)pyridine

DPPA is diphenylphosphoryl azide

DPPP is 1,3-bis(diphenylphosphino)propane

DBU is 1,8-diazabicyclo[5.4.0]undec7-ene

NaH is sodium hydride

brine is saturated aqueous sodium chloride solution

TLC is thin layer chromatography

LDA is lithium diisopropylamide

BOP-Cl is bis(2-oxo-3-oxazolidinyl)phosphinic chloride

NMP is N-methyl pyrrolidinone

Lawesson's reagent is[2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulfide]

EXAMPLES Example 1N-[[1-(2-Methoxyethyl)cyclopentyl]thioxomethyl]-4-nitro-L-phenylalanineMethyl Ester

To a solution of[[1-(2-methoxyethyl)cyclopentyl]carbonyl]-4-nitro-L-phenylalanine methylester (4.30 g, 11.4 mmol) in toluene (20 mL) was added Lawesson'sreagent (2.60 g, 6.27 mmol). The resultant mixture was warmed to 50° C.and stirred for 18 h. The reaction mixture was filtered through asintered glass funnel and the filtrate was concentrated in vacuo. Theresidue was by flash column chromatography over silica gel (hexane-ethylacetate, 9:1 then 8:1) to affordN-[[1-(2-methoxyethyl)cyclopentyl]thioxomethyl]-4-nitro-L-phenylalaninemethyl ester (2.44 g, 54%; 70% based on recovered starting material) asa light yellow oil. HR MS: Obs. mass, 395.1639. Calcd. mass, 395.1640(M+H).

Example 24-[[(2,6-Dichlorophenyl)carbonyl]amino]-N-[[1-(2-(methoxyethyl)cyclopentyl]thioxomethyl]-L-phenylalanineMethyl Ester

To a suspension ofN-[[1-(2-methoxyethyl)cyclopentyl]thioxomethyl]-4-nitro-L-phenylalaninemethyl ester (4.58 g, 11.6 mmol), zinc dust (7.50 g, 116 mmol) andammonium chloride (9.20 g, 174 mmol) in methanol (200 mL) was added H₂O(100 mL) slowly over 5 min. After stirring for 20 min, the reactionmixture was partitioned between ethyl acetate (400 mL) and sat. ammoniumchloride solution (150 mL). The separated aqueous layer wasback-extracted with ethyl acetate (3×100 mL) and the organic layers werecombined, dried over Na₂SO₄, filtered and concentrated in vacuo. Theresidual oil was dried under high vacuum for 2 h to give crude4-amino-N-[[1-(2-methoxyethyl)cyclopentyl]thioxomethyl]-L-phenylalaninemethyl ester (4.5 g).

To a solution of the crude amine obtained above (3.40 g, ˜8.77 mmolbased on 94% purity) and diisopropylethylamine (1.70 mL, 9.65 mmol) indichloromethane (15 mL) was added a solution of 2,6-dichlorobenzoylchloride (1.9 g, 9.21 mmol) in dichloromethane (5 mL). The resultantmixture was stirred overnight, then was concentrated in vacuo andtransferred to a separatory funnel containing ethyl acetate (150 mL) andwater (40 mL). The aqueous layer was separated and back extracted withethyl acetate (1×50 mL). The combined organic layer was washed with asat. solution of Na₂CO₃ followed by brine, dried over MgSO₄, filteredand concentrated in vacuo. The reaction product by silica gel flashcolumn chromatography (hexane-ethyl acetate, 3:1) to give4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[1-(2-methoxyethyl)cyclopentyl]thioxomethyl]-L-phenylalaninemethyl ester (4.50 g, 95%). HR MS: Obs. mass, 559.1201. Calcd. mass,559.1201 (M+Na).

Example 34-[[(2,6-Dichlorophenyl)carbonyl]amino]-N-[[1-(2-methoxyethyl)cyclopentyl]thioxomethyl]-L-phenylalanine

To a solution of4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[1-(2-methoxyethyl)cyclopentyl]thioxomethyl]-L-phenylalanine methyl ester (4.00 g, 7.44mmol) in methanol (18 mL) was added a solution of NaOH (421 mg, 10.5mmol) in water (3 mL). The mixture was stirred for 2 h and thenacidified (pH˜1-2) with 0.5N HCl. The reaction mixture was poured into aseparatory funnel containing ethyl acetate (150 mL) and water (25 mL).The separated aqueous layer was back-extracted with ethyl acetate (2×50mL). The combined organic layers was washed with brine, dried overMgSO₄, filtered and concentrated in vacuo. Purification of the residualmaterial by RP-HPLC (15-95% acetonitrile-water gradient over 25 min)provided4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[1-(2-methoxyethyl)cyclopentyl]thioxomethyl]-L-phenylalanine(3.05 g, 78%). HR MS: Obs. mass, 545.1043. Calcd. mass, 545.1045 (M+Na).

Example 4 1-(2-azidoethyl)cyclopentanecarboxylic Acid

To an ice cold solution of diisopropylamine (56 mL, 0.396 mol) in THF(85 mL) was added n-butyl lithium in hexane solution (240 mL, 1.6 M,0.393 mol) over 20 min. The mixture was stirred at 0° C. for 30 min,cooled to a bath temperature of −65° C. and ethylcyclopentanecarboxylate (37.4 g, 0.263 mol) in THF (50 mL) was addedover 20 min. After 1 h, a solution of 1,2-dibromoethane (47 mL, 0.545mol) in THF (50 mL) was added, the mixture was held at −65° C. for 3 hand then was allowed to warm to room temperature overnight. After thereaction was quenched by addition of saturated ammonium chloridesolution (200 mL), the layers were separated and the aqueous layer wasextracted with ethyl acetate (100 mL). The combined extracts were washedwith 1:1 brine:water (250 mL) and were dried (Na₂SO₄). The solution wasfiltered, concentrated in vacuo then the residue was diluted withtoluene (100 mL) and concentrated. The dilution and concentration cyclewas repeated twice to give ethyl 1-(2-bromoethyl)cyclopentanecarboxylate(52.5 g).

A solution of the above bromide (52.5 g, 0.211 mol) and sodium azide (54g, 0.831 mol) in DMF (200 mL) was stirred at 50° C. for 5 h under anitrogen atmosphere and was filtered. The filtrate was concentrated tonear dryness, diluted with ethyl acetate (500 mL), filtered andconcentrated to give crude ethyl 1-(2-azidoethyl)cyclopentanecarboxylate(40.9 g) as a brown oil. This material was combined with product from aprevious run (total 63.5 g) and was purified by chromatography over 250g of silica gel (5% ethyl acetate in hexane) to give 50.3 g of productas a light brown oil.

The oil from above (50.3 g, 0.238 mol) was dissolved in THF (750 mL) andmethanol (375 mL) and a solution of LiOH hydrate (15 g, 0.357 mol) inwater (300 mL) was added. The resulting solution was stirred at 40° C.overnight and concentrated. The residue was dissolved in 2 L of watercontaining 40 mL of 1N NaOH and was washed with hexane (1 L). Theaqueous layer was treated with 1 N HCl (375 mL) and was extracted withdiethyl ether (2×1 L). The combined extracts were dried (Na₂SO₄),filtered and concentrated under reduced pressure to give1-(2-azidoethyl)cyclopentane carboxylic acid (37.5 g) as an amberliquid.

Example 5N-[[1-(2-Azidoethyl)cyclopentyl]carbonyl]-4-nitro-L-phenylalanine MethylEster

A solution of 4-nitro-L-phenylalanine methyl ester hydrochloride (3.0 g,11.5 mmol), 1-(2-azidoethyl)cyclopentane carboxylic acid (2.3 g, 12.7mmol) and BOP (5.34 g, 12.1 mmol) in dichloromethane (6 mL) and DMF (4mL) was treated with diisopropylethylamine (4.2 mL, 24.2 mmol). Themixture was stirred overnight at which time TLC (1:1 hexane:ethylacetate) indicated no more starting material. The mixture was dilutedwith water, extracted with ethyl acetate. The extracts were washed withwater and brine, then were dried (Na₂SO₄), filtered and evaporated invacuo. The residue was purified by chromatography over silica gel(3:1hexane:ethyl acetate) to afford 4.26 g ofN-[[1-(2-azidoethyl)cyclopentyl]carbonyl]-4-nitro-L-phenylalanine methylester.

Example 6N-[[1-[2-[[(1,1-Dimethylethoxy)carbonyl]amino]ethyl]cyclopentyl]carbonyl]-4-nitro-L-phenylalanineMethyl Ester

a. A solution ofN-[[1-(2-azidoethyl)cyclopentyl]carbonyl]-4-nitro-L-phenylalanine methylester (1.92 g, 4.93 mmol) in THF (20 mL) was treated dropwise with a 1 Msolution of trimethylphosphine in THF. After the addition was complete,the mixture was stirred for 20 min and water (0.17 mL) was added. Thereaction was stirred a further 2 h, then a little trifluoroacetic acidwas added and the mixture was dried over sodium sulfate andconcentrated.

b. To a solution ofN-[[1-(2-aminoethyl)cyclopentyl]carbonyl]-4-nitro-L-phenylalanine methylester trifluoroacetic acid salt (2.35 g, 4.93 mmol) in dioxane (25 mL)was added diisopropylethylamine (0.860 mL, 4.93 mmol) and di-tert-butyldicarbonate (1.08 g, 4.93 mmol). The resultant mixture was stirred for18 h. The reaction mixture was filtered through a sintered glass funneland the filtrate was concentrated in vacuo. Purification of the residualmaterial by silica gel flash column chromatography (hexane-ethyl acetate3:1) affordedN-[[1-[2-[[(1,1-dimethylethoxy)carbonyl]amino]ethyl]cyclopentyl]carbonyl]-4-nitro-L-phenylalaninemethyl ester (2.20 g, 95%). HR MS: Obs. mass, 464.2397. Calcd. mass,464.2397 (M+H).

Example 7N-[[1-[2-[[(1,1-Dimethylethoxy)carbonyl]amino]ethyl]cyclopentyl]thioxomethyl]4-nitro-L-phenylalanineMethyl Ester

To a solution ofN-[[1-[2-[[(1,1-dimethylethoxy)carbonyl]amino]ethyl]cyclopentyl]carbonyl]-4-nitro-L-phenylalaninemethyl ester (1.00 g, 2.16 mmol) in toluene/dioxane (1:1, 10 mL) wasadded Lawesson's reagent (0.524 g, 1.29 mmol). The resultant mixture waswarmed to 50° C. and was stirred for 24 h. The reaction mixture wasfiltered through a sintered glass funnel and the filtrate wasconcentrated in vacuo. Purification of the crude product by silica gelflash column chromatography (hexane-ethyl acetate, 6:1 then 4:1),affordedN-[[1-[2-[[(1,1-dimethylethoxy)carbonyl]amino]ethyl]cyclopentyl]thioxomethyl]-4-nitro-L-phenylalaninemethyl ester (460 mg, 44%; 65% based on recovered starting material) asa light yellow oil. HR MS: Obs. mass, 478.2014. Calcd. mass, 478.2012(M−H).

Example 8N-[[1-[2-(Acetylamino)ethyl]cyclopentyl]thioxomethyl]-4-nitro-L-phenylalanineMethyl Ester

To a solution ofN-[[1-[2-[[(1,1-dimethylethoxy)carbonyl]amino]ethyl]cyclopentyl]thioxomethyl]-4-nitro-L-phenylalaninemethyl ester (1.26 g, 2.63 mmol) in dichloromethane (15 mL) was addeddropwise trifluoroacetic acid (7 mL) and the resultant mixture wasstirred for 2 h at room temperature. The reaction mixture wasconcentrated in vacuo to afford the trifluoroacetic acid salt of crudeN-[[1-(2-aminoethyl)cyclopentyl]thioxomethyl]-4-nitro-L-phenylalaninemethyl ester as a yellow oil (1.4 g).

To a solution of the salt obtained above (1.4 g, ˜2.63 mmol) indichloromethane (10 mL) was added diisopropylethylamine (1.37 mL, 7.88mmol) and acetic anhydride (0.250 mL, 2.63 mmol). The resultant mixturewas stirred overnight. The reaction mixture was concentrated in vacuoand transferred to a separatory funnel containing ethyl acetate (100 mL)and water (40 mL). The aqueous layer was separated and back extractedwith ethyl acetate (1×50 mL). The combined organic layer was washed withbrine, dried over MgSO₄, filtered and concentrated in vacuo. Theresulting residue was purified by flash column chromatography(dichloromethane-acetone, 5:1) to furnishN-[[1-[2-(acetylamino)ethyl]cyclopentyl]thioxomethyl]-4-nitro-L-phenylalaninemethyl ester (743 mg, 67%). HR MS: Obs. mass, 422.1744. Calcd. mass,422.1750 (M+H).

Example 94-Amino-N-[[1-[2-acetylamino)ethyl]cyclopentyl]thioxomethyl]-L-phenylalanineMethyl Ester

To a suspension ofN-[[1-[2-(acetylamino)ethyl]cyclopentyl]thioxomethyl]-4-nitro-L-phenylalaninemethyl ester (740 mg, 1.75 mmol), zinc dust (1.14 g, 17.5 mmol) andammonium chloride (1.41 g, 26.3 mmol) in methanol (20 mL) was added H₂O(10 mL) slowly over 5 min. After stirring for 20 min, the reactionmixture was diluted with ethyl acetate (80 mL) and sat. ammoniumchloride solution (25 mL). The separated aqueous layer wasback-extracted with ethyl acetate (3×25 mL) and the organic layers werecombined, dried over Na₂SO₄, filtered and concentrated in vacuo. Theresidual oil was dried under high vacuum for 2 h to give the crude amine(750 mg)which was by flash silica gel column chromatography(dichloromethane-acetone 2:1) to furnish4-amino-N-[[1-[2-acetylamino)ethyl]cyclopentyl]thioxomethyl]-L-phenylalaninemethyl ester (650 mg, 95%). HR MS: Obs. mass, 392.2016. Calcd. mass,392.2008 (M+H).

Example 10 N-[[1-[2-(Acetylamino)ethyl]cyclopentyl]thioxomethyl]-4-[[(2,6-dichlorophenyl)carbonyl]amino]-L-phenylalanine

To a solution of4-amino-N-[[1-[2-(acetylamino)ethyl]cyclopentyl]thioxomethyl]-L-phenylalaninemethyl ester (195 mg, 0.498 mmol) and diisopropylethylamine (0.0950 mL,0.548 mmol) in dichloromethane (1 mL) was added a solution of2,6-dichlorobenzoyl chloride (110 mg, 0.523 mmol) in dichloromethane (1mL). The resultant mixture was stirred overnight then was concentratedin vacuo and transferred to a separatory funnel containing ethyl acetate(50 mL) and water (10 mL). The separated aqueous layer back-extractedwith ethyl acetate (1×25 mL). The combined organic layer was washed inturn sat. solution of Na₂CO₃ and brine, then was dried over MgSO₄,filtered and concentrated in vacuo to provide crudeN-[[1-[2-(acetylamino)ethyl]cyclopentyl]thioxomethyl]-4-[[(2,6-dichlorophenyl)carbonyl]amino]-L-phenylalaninemethyl ester (300 mg).

To a solution of the above methyl ester (300 mg, 0.498 mmol) in methanol(1 mL) was added a solution of NaOH (64 mg, 14.9 mmol) in water (1 mL).The mixture was stirred for 2 h and was then acidified (pH˜1-2) with0.5M HCl. The reaction mixture was poured into a separatory funnelcontaining ethyl acetate (50 mL) and water (10 mL) and the separatedaqueous layer was back-extracted with ethyl acetate (2×25 mL). Thecombined organic layers were washed with brine, dried over MgSO₄,filtered and concentrated in vacuo. Purification of the crude by RP-HPLC(15-95% acetonitrile-water gradient over 25 min) and lyophylization ofthe appropriate fractions, provided N-[[1-[2-(acetylamino)ethyl]cyclopentyl]thioxomethyl]-4-[[(2,6-dichlorophenyl)carbonyl]amino]-L-phenylalanine(126 mg, 46%) as a colorless solid. HR MS: Obs. mass, 550.1330. Calcd.mass, 550.1334 (M+H).

Example 114-[[(2,6-Dichlorophenyl)carbonyl]amino]-N-[[1-[2-[[(methylamino)carbonyl]amino]ethyl]cyclopentyl]thioxomethyl]-L-phenylalanine

4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[1-[2-[[(methylamino)carbonyl]amino]ethyl]cyclopentyl]thioxomethyl]-L-phenylalaninewas prepared fromN-[[1-[2-[[(1,1-dimethylethoxy)carbonyl]amino]ethyl]cyclopentyl]thioxomethyl]-4-nitro-L-phenylalaninemethyl ester and methyl isocyanate by using the general proceduredescribed in examples 8 to 10. HR MS: Obs. mass, 565.1436. Calcd. mass,565.1443 (M+H).

Example 12 2-Chloro-6-methylbenzaldehyde.

A 500 mL, three-necked, round bottomed flask equipped with a magneticstirrer, thermometer, addition funnel, and argon inlet was charged with75 g (494 mmol) of 2-chloro-6-methylbenzonitrile and 400 mL of toluene(stored over 4 Å molecular sieves). The mixture was cooled to −2° C.(ice/acetone bath) and a 1M solution of DIBAL-H in hexanes (593 mmol,593 mL) was added dropwise over a period of 30 min while maintaining thetemperature below 0° C. After the addition was completed, the reactionmixture was stirred for 1 h at 0° C. and then allowed to warm to roomtemperature. After 2 h at room temperature, TLC analysis indicated theabsence of starting material (4:1 hexane:diethyl ether, phosphomolybdicacid spray, as analysis by UV fluorescence was misleading). The reactionwas poured into a mixture of ice (2000 g) and concentrated sulfuric acid(50 mL) and was stirred for overnight. The precipitated solids werecollected by filtration and the filtrate was extracted with diethylether (2×200 mL). The combined extracts were washed with brine, dried(MgSO₄) and filtered. Evaporation of the solvent under reduced pressuregave the crude aldehyde, which was combined with the above solid toafford 71.31 g (93%) of light yellow colored aldehyde suitable for usein the next step.

Example 13 2-Chloro-6-methylbenzoic Acid

A 1000 mL, three-necked, round bottomed flask equipped with a magneticstirrer, thermometer, addition funnel, and argon inlet was charged with2-chloro-6-methylbenzaldehyde (71.31 g, 461 mmol, crude obtained fromthe above experiment) and 750 mL of acetonitrile. To this suspension, asolution of monobasic sodium phosphate (115 mmol, 15.9 g) in water 240mL) was added followed by hydrogen peroxide (50 mL, 30%) at roomtemperature. Then, a solution of sodium chlorite (73.5 g, 811 mmol) inwater (700 mL) was added dropwise at 0° C. while maintaining thetemperature below 3° C. After the addition was complete, the yellowsuspension was stirred for 15 h at 0° C. to room temperature. TLCanalysis of the mixture indicated the absence of starting material. Asolution of sodium bisulfite (73 g, 701 mmol) in water (200 mL) wasadded dropwise at 0° C. until the yellow color disappeared (KI-paperpositive). Cooling was maintained throughout to control the exothermicreaction. The solvent was removed under vacuum to afford a colorlesssolid. The solid was collected by filtration and the filtrate wasextracted with diethyl ether (200 mL). The above solid was dissolved inthe combined diethyl ether extracts which were then washed with 10% NaOHsolution (2×200 mL). The combined aqueous washings were acidified with10% HCl to ˜pH 1. The resulting colorless precipitate was collected byfiltration and air-dried to afford 54.88 g (65%, overall in two steps)of 2-chloro-6-methylbenzoic acid as a colorless solid.

Example 14 N-[(2-Chloro-6-methylphenyl)carbonyl]-4-nitro-L-phenylalanineMethyl Ester

To a solution of 4-nitro-L-phenylalanine methyl ester hydrochloride salt(7.44 mmol, 1.94 g), 2-chloro-6-methylbenzoic acid (8.2 mmol, 1.4 g) andHBTU (8.2 mmol, 3.11 g) in DMF (27 mL) was added diisopropylethylamine(18.6 mmol, 3.24 mL) at room temperature. The clear solution was stirredfor 48 h at room temperature and was diluted with 100 mL of ethylacetate. The solution was washed in turn with 0.5N hydrochloric acid(2×50 mL), saturated sodium bicarbonate solution (2×50 mL), brine (100mL) then was dried (MgSO₄) and filtered. Concentration of the solutionto dryness gave 2.67 g (95%) ofN-[(2-chloro-6-methylphenyl)carbonyl]-4-nitro-L-phenylalanine methylester as a colorless solid, mp 120-123° C. HRMS: Obs. mass, 376.4274.Calcd. mass, 376.4238 (M+H).

Example 15N-[(2-Chloro-6-methylphenyl)thioxomethyl]-4-nitro-L-phenylalanine MethylEster

To a mixture ofN-[(2-chloro-6-methylphenyl)carbonyl]-4-nitro-L-phenylalanine methylester (9.66 mmol, 3.64 g) and Lawesson's reagent (6.0 mmol, 2.46 g, 0.62equiv.) was added toluene (15 mL, which had been stored over 4 Åmolecular sieves) at room temperature. The suspension was heated to90-100° C. and was stirred for 24 h. Examination of the resulting clearsolution by TLC failed to detect the presence of starting material. Thereaction mixture was diluted with ethyl acetate (50 mL) and washed withwater (50 mL), saturated sodium bicarbonate solution (50 mL), and brine(50 mL). The organic extract was dried (MgSO₄) filtered and evaporatedunder reduced pressure. The crude compound was purified by carefulsilica gel column chromatography (hexane:ethyl acetate, 4:1 to 2:1) toobtain 1.52 g (40%) ofN-[(2-chloro-6-methylphenyl)thioxomethyl]-4-nitro-L-phenylalanine methylester as a yellow solid, mp 150-153° C. (triturated from diethyl ether/hexane 3:1 ratio). HRMS: Obs. mass, 393.0685. Calcd. mass, 393.0677(M+H).

Example 164-Amino-N-[(2-chloro-6-methylphenyl)thioxomethyl]-L-phenylalanine MethylEster

To a mixture ofN-[(2-chloro-6-methylphenyl)thioxomethyl]-4-nitro-L-phenylalanine methylester (3.86 mmol, 1.52 g), zinc dust (˜325 mesh, 39.0 mmol, 2.55 g, 10equiv.) and ammonium chloride (58.0 mmol, 3.09 g, 15 equiv.) was addedmethanol (50 mL) and water (25 mL) at room temperature. After additionof water, an exothermic reaction ensued and the temperature rose tobetween 45 and 50° C. After the suspension was stirred for 2 h at a bathtemperature of 50-60° C., TLC analysis of the mixture indicated theabsence of starting material. The reaction mixture was filtered througha pad of celite and the filter cake was washed with methanol (50 mL) andwater (40 mL). The filtrate was concentrated under vacuum to removemethanol and the product was extracted into ethyl acetate (2×50 mL). Thecombined extracts were washed with brine (50 mL), dried (MgSO₄),filtered and concentrated in vacuo to give 1.3 g (92%) of4-amino-N-[(2-chloro-6-methylphenyl)thioxomethyl]-L-phenylalanine methylester as an amorphous yellow solid, which was used directly for nextstep. HRMS: Obs. mass, 363.0932. Calcd. mass, 363.0934 (M+H).

Example 17N-[(2-Chloro-6-methylphenyl)thioxomethyl]-4-[[(2,6-dichlorophenyl)carbonyl]amino]-L-phenylalanineMethyl Ester

To a solution of4-amino-N-[(2-chloro-6-methylphenyl)thioxomethyl]-L-phenylalanine methylester (3.57 mmol, 1.296 g) and 2,6-dichlorobenzoyl chloride (3.75 mmol,0.785 g) in dichloromethane (20 mL) was added diisopropylethylamine(5.35 mmol, 0.93 mL) at room temperature. The solution was stirred for15 h at which time TLC analysis of the mixture indicated the absence ofstarting material. After the addition of water (30 mL), the layers wereseparated and the aqueous phase was extracted with dichloromethane (20mL). The combined extracts were washed with brine (50 mL), dried (MgSO₄)and concentrated under reduced pressure. The residue was purified bysilica gel column chromatography ( hexane:ethyl acetate, 4:1 to 1:1) toobtain 1.91 g (83%) ofN-[(2-chloro-6-methylphenyl)thioxomethyl]-4-[[(2,6-dichlorophenyl)carbonyl]amino]-L-phenylalaninemethyl ester as an amorphous colorless solid. HRMS: Obs. mass, 535.0399.Calcd. mass, 535.0416 (M+H).

Example 184-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[(2-chloro-6-methylphenyl)thioxomethyl]-L-phenylalanine.

To a suspension ofN-[(2-chloro-6-methylphenyl)thioxomethyl]-4-[[(2,6-dichlorophenyl)carbonyl]amino]-L-phenylalaninemethyl ester (2.89 mmol, 1.55 g) in ethanol (8 mL) was added aqueous1.0N sodium hydroxide (5 mL) at room temperature. The mixture was heatedto 50-55° C. and the resulting clear solution was stirred for 3-4 h. TLCanalysis of the mixture indicated the absence of starting material. Themixture was concentrated to remove ethanol, then was diluted with 15 mLof water and extracted with 25 mL of diethyl ether to remove any neutralimpurities. The aqueous layer was acidified with 1N HCl and theprecipitated colorless solid was extracted into ethyl acetate (2×30 mL).The combined extracts were washed with brine, dried (MgSO₄) andconcentrated in vacuo to afford 1.45 g (96%) ofN[(2-chloro-6-methylphenyl)thioxomethyl]-4-[[(2,6-dichlorophenyl)carbonyl]amino]-L-phenylalanineas an amorphous colorless solid. HRMS: Obs. mass, 521.0241. Calcd. mass,521.0260 (M+H).

Example 19N-[(2-Chloro-6-methylphenyl)thioxomethyl]-4-[[(2,6-dichlorophenyl)carbonyl]amino]-L-phenylalanineSodium Salt

N-[(2-chloro-6-methylphenyl)thioxomethyl]-4-[[(2,6-dichlorophenyl)carbonyl]amino]-L-phenylalanine(2.77 mmol, 1.45 g) was dissolved in water (10 mL) containing 1.5equivalents of aqueous 1.0N sodium hydroxide (4.2 mL) at roomtemperature. The solution was loaded into a reverse phase column size of8 inches length with 1.5 inches diameter containing C-18 silica gel andeluted with water to remove excess base. The product was eluted with5-20% methanol in water. After the appropriate fractions were combinedand concentrated, the residue was dissolved in 50 mL water andlyophilized to afford 1.3 g of the sodium salt as a colorless amorphoussolid. HRMS: Obs. mass, 543.0076. Calcd. mass, 543.0079 (M+H).

Example 20 2-Ethyl-6-methylbenzoic Acid

A 250 mL pressure bottle was charged with 2-ethyl-6-methyliodobenzene(30.07 mmol, 7.4 g), Pd(OAc)₂ (1.43 mmol, 334 mg) and dppp (1.43 mmol,620 mg). The flask was closed with a septum and evacuated three timeswith argon. Acetonitrile (96 mL), triethylamine (189 mmol, 19.0 g, 26.25mL) and water (19.1 mL) were added in succession by the aid of syringeand the rubber septum was replaced with a teflon lined cap connected toa carbon monoxide source. The flask was now pressurized with carbonmonoxide (40 psi) and the excess pressure was released. This process wasrepeated three times and finally the mixture was stirred for 5 min under40 psi carbon monoxide pressure. The flask was then disconnected fromthe carbon monoxide cylinder and immersed in a preheated oil bath(83-85° C.). The reaction mixture turned black within 1 h and wasstirred for another 14 h at this temperature, then was cooled to roomtemperature and the pressure was released. The resulting mixture wasdiluted with diethyl ether (200 mL) and 1.0N NaOH (20 mL). The formedsodium was extracted into water (2×100 mL). The combined water extractswere acidified with 1.0N HCl and the mixture was extracted withdichloromethane (3×100 mL). The combined dichloromethane extracts werewashed with brine, dried (MgSO₄), filtered and the volatiles wereremoved under vacuum to provide 3.58 g (72.5%) of2-ethyl-6-methylbenzoic acid as a viscous brown oil which slowlysolidified overnight. HR MS: Obs. mass, 164.0833. Calcd. mass, 164.0837(M+).

Example 21 N-[(2-Ethyl-6-methylphenyl)carbonyl]-4-nitro-L-phenylalanineMethyl Ester

Using the procedure described in example 14,N-[(2-ethyl-6-methylphenyl)carbonyl]-4-nitro-L-phenylalanine methylester was prepared in 72% yield as a colorless solid, mp 119-121° C. HRMS: Obs. mass, 371.1610. Calcd. mass, 371.1607 (M+H).

Example 22N-[(2-Ethyl-6-methylphenyl)thioxomethyl]-4-nitro-L-phenylalanine MethylEster

Using the procedure described in example 15,N-[(2-ethyl-6-methylphenyl)thioxomethyl]-4-nitro-L-phenylalanine methylester was prepared in 47% yield as an amorphous colorless solid. HR MS:Obs. mass, 387.1383. Calcd. mass, 387.1378 (M+H).

Example 234-Amino-N-[(2-ethyl-6-methylphenyl)thioxomethyl]-L-phenylalanine MethylEster

Using the general procedure described in example 16,4-amino-N-[(2-ethyl-6-methylphenyl)thioxomethyl]-L-phenylalanine methylester was prepared in 94% yield as an amorphous colorless solid. HR MS:Obs. mass, 357.1640. Calcd. mass, 357.1638 (M+H).

Example 244-[[(2,6-Dichlorophenyl)carbonyl]amino]-N-[(2-ethyl-6-methylphenyl)thioxomethyl]-L-phenylalanineMethyl Ester

Using the procedure described in example 17,4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[(2-ethyl-6-methylphenyl)thioxomethyl]-L-phenylalaninemethyl ester was prepared in 70% yield as an amorphous colorless solid.HR MS: Obs. mass, 529.1094. Calcd. mass, 529.1119 (M+H).

Example 254-[[(2,6-Dichlorophenyl)carbonyl]amino]-N-[(2-ethyl-6-methylphenyl)thioxomethyl]-L-phenylalanine

Using the procedure described in example 18,4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[(2-ethyl-6-methylphenyl)thioxomethyl]-L-phenylalaninewas prepared in 77% yield as an amorphous colorless solid. HR MS: Obs.mass, 515.0942. Calcd. mass, 515.0963 (M+H).

Example 26N-[(2-Ethyl-6-methylphenyl)thioxomethyl]-4-[[(2R)-2-(Fmoc-amino)-1-oxo-3-(pyridin-3-yl)propyl]amino]-L-phenylalanineMethyl Ester

Using the procedure described in example 1,N-[(2-ethyl-6-methylphenyl)thioxomethyl]-4-[[(2R)-2-(Fmoc-amino)-1-oxo-3-(pyridin-3-yl)propyl]amino]-L-phenylalaninemethyl ester was prepared in 72% yield as an amorphous colorless solid.HR MS: Obs. mass, 727.2973. Calcd. mass, 727.2954 (M+H).

Example 274-[[(2R)-2-Amino-1-oxo-3-(pyridin-3-yl)propyl]amino]-N-[(2-ethyl-6-methylphenyl)thioxomethyl]-L-phenylalanineMethyl Ester

N-[(2-ethyl-6-methylphenyl)thioxomethyl]-4-[[(2R)-2-(Fmoc-amino)-1-oxo-3-(pyridin-3-yl)propyl]amino]-L-phenylalaninemethyl ester from example 26 (0.308 mmol, 224 mg) was treated with 25%piperidine in NMP (3 mL) and the solution was stirred at roomtemperature. Within 1 h, TLC analysis of the mixture indicated theabsence of starting material. The mixture was diluted with hexane (25mL) and the formed layers were separated. The bottom yellow layer waswashed with hexane, then was diluted with water and extracted with ethylacetate and THF (2:1, 3×25 mL). The combined extracts were washed withwater (50 mL), brine (50 mL), dried (MgSO₄), filtered and the solventswere removed under vacuum. The resulting residue was dried under highvacuum to afford 126 mg (81%) of4-[[(2R)-2-amino-1-oxo-3-(pyridin-3-yl)propyl]amino]-N-[(2-ethyl-6-methylphenyl)thioxomethyl]-L-phenylalaninemethyl ester as an amorphous colorless solid. HR MS: Obs. mass,505.2270. Calcd. mass, 505.2274 (M+H).

Example 284-[(2S,4R)-3-Acetyl-5-oxo-2-phenyl-4-[(pyridin-3-yl)methyl]imidazolidin-1-yl]-N-[(2-ethyl-6-methylphenyl)thioxomethyl]-L-phenylalanineMethyl Ester

To a solution of4-[[(2R)-2-amino-1-oxo-3-(pyridin-3-yl)propyl]amino]-N-[(2-ethyl-6-methylphenyl)thioxomethyl]-L-phenylalaninemethyl ester (0.224 mmol, 113 mg) in dichloromethane (0.75 mL) andtrimethyl orthoformate (0.75 mL), was added benzaldehyde (0.25 mmol,27.5 mg). After the resulting light yellow solution was stirred for 3days at room temperature, it was heated to 90° C. (oil bath temperature)and excess acetic anhydride (2.0 mmol, 0.21 mL) was introduced via asyringe. The solution was stirred at 110-120° C. (oil bath temperature)for 6 h, then was cooled to room temperature and the solvents wereremoved in vacuo. The crude residue was purified by RP-HPLC to obtain 95mg (67%) of4-[(2S,4R)-3-acetyl-5-oxo-2-phenyl-4-[(pyridin-3-yl)methyl]imidazolidin-1-yl]-N-[(2-ethyl-6-methylphenyl)thioxomethyl]-L-phenylalaninemethyl ester as an amorphous colorless solid. HR MS: Obs. mass,635.2672. Calcd. mass, 635.2692 (M+H). Another isomer was formed in veryminor amount by HPLC (<5%) and not attempted to isolate it.

Example 294-[(2S,4R)-3-Acetyl-5-oxo-2-phenyl-4-[(pyridin-3-yl)methyl]imidazolidin-1-yl]-N-[(2-ethyl-6-methylphenyl)thioxomethyl]-L-phenylalanine

The hydrolysis of4-[(2S,4R)-3-acetyl-5-oxo-2-phenyl-4-[(pyridin-3-yl)methyl]imidazolidin-1-yl]-N-[(2-ethyl-6-methylphenyl)thioxomethyl]-L-phenylalaninemethyl ester was carried out using the general procedure described inexample 18. The obtained crude product was purified by RP-HPLC, using a5-95% acetonitrile-water gradient over 30 min and the appropriatefraction was collected. The acetonitrile was removed under vacuum andthe product was extracted into ethyl acetate:THF (3:1) (2×25 mL). Thecombined extracts were washed with brine, dried (MgSO₄), filtered andthe solvents were removed under reduced pressure. The resulting residuewas dried under high vacuum to obtain4-[(2S,4R)-3-acetyl-5-oxo-2-phenyl-4-[(pyridin-3-yl)methyl]imidazolinidin-1-yl]-N-[(2-ethyl-6-methylphenyl)thioxomethyl]-L-phenylalaninein 30% yield as an amorphous colorless solid. HR MS: Obs. mass,621.2520. Calcd. mass, 621.2535 (M+H).

Example 30 N-[(2-Fluorophenyl)carbonyl]-4-nitro-L-phenylalanine MethylEster

Using the general procedure described in example 14, starting with4-nitro-L-phenylalanine methyl ester hydrochloride salt and2-fluorobenzoic acid,N-[(2-fluorophenyl)carbonyl]-4-nitro-L-phenylalanine methyl ester wasprepared in 99% yield as a colorless solid, mp 137-139° C. HR MS: Obs.mass, 346.0977. Calcd. mass, 346.0980, M+.

Example 31 N-[(2-Fluorophenyl)thioxomethyl]-4-nitro-L-phenylalanineMethyl Ester

Using the general procedure described in example 15, starting withN-[(2-fluorophenyl)carbonyl]-4-nitro-L-phenylalanine methyl ester,N-[(2-fluorophenyl)thioxomethyl]-4-nitro-L-phenylalanine methyl esterwas prepared in 99% yield as an amorphous colorless solid. HR MS: Obs.mass, 363.0816. Calcd. mass, 363.0815 (M+H).

Example 32 4-Amino-N-[(2-fluorophenyl)thioxomethyl]-L-phenylalanineMethyl Ester

Using the general procedure described in example 16, starting withN-[(2-fluorophenyl)thioxomethyl]-4-nitro-L-phenylalanine methyl ester,4-amino-N-[(2-fluorophenyl)thioxomethyl]-L-phenylalanine methyl esterwas prepared in 87% yield as an amorphous colorless solid. HR MS: Obs.mass, 332.1042. Calcd. mass, 332.1046, (M+H).

Example 334-[[(2,6-Dichlorophenyl)carbonyl]amino]-N-[(2-fluorophenyl)thioxomethyl]-L-phenylalanineMethyl Ester

Using the general procedure described in example 17, starting with4-amino-N-[(2-fluorophenyl)thioxomethyl]-L-phenylalanine methyl esterand 2,6-dichlorobenzoyl chloride,4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[(2-fluorophenyl)thioxomethyl]-L-phenylalaninemethyl ester was prepared in 74% yield as an amorphous colorless solid.HR MS: Obs. mass, 505.0561. Calcd. mass, 505.0555, (M+H).

Example 344-[[(2,6-Dichlorophenyl)carbonyl]amino]-N-[(2-fluorophenyl)thioxomethyl]-L-phenylalanine

Using the general procedure described in example 18, starting with4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[(2-fluorophenyl)thioxomethyl]-L-phenylalaninemethyl ester,4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[(2-fluorophenyl)thioxomethyl]-L-phenylalaninewas prepared in 89% yield as an amorphous colorless solid. HR MS: Obs.mass, 491.0407. Calcd. mass, 491.0399 (M+H).

Example 354-Nitro-N-[[(2-(trifluoromethyl)phenyl]carbonyl]-L-phenylalanine MethylEster

Using the general procedure described in example 14, starting with4-nitro-L-phenylalanine methyl ester hydrochloride salt and2-trifluoromethylbenzoic acid,4-nitro-N-[[(2-(trifluoromethyl)phenyl]carbonyl]-L-phenylalanine methylester was prepared in 69% yield as a colorless solid, mp 152-154° C. HRMS: Obs. mass, 397.1017. Calcd. mass, 397.1011 (M+H).

Example 364-Nitro-N-[[2-(trifluoromethyl)phenyl]thioxomethyl]-L-phenylalanineMethyl Ester

Using the general procedure described in example 15, starting with4-nitro-N-[[(2-(trifluoromethyl)phenyl]carbonyl]-L-phenylalanine methylester,4-nitro-N-[[2-(trifluoromethyl)phenyl]thioxomethyl]-L-phenylalaninemethyl ester was prepared in 67% yield as an amorphous colorless solid.HR MS: Obs. mass, 412.0752. Calcd. mass, 412.0757 (M+H).

Example 374-Amino-N-[[2-(trifluoromethyl)phenyl]thioxomethyl]-L-phenylalanineMethyl Ester

Using the general procedure described in example 16, starting with4-nitro-N-[[2-(trifluoromethyl)phenyl]thioxomethyl]-L-phenylalaninemethyl ester,4-amino-N-[[2-(trifluoromethyl)phenyl]thioxomethyl]-L-phenylalaninemethyl ester was prepared in 98% yield as an amorphous colorless solid.HR MS: Obs. mass, 382.1072. Calcd. mass, 382.1078, (M+H).

Example 384-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[2-(trifluoromethyl)phenyl]thioxomethyl]-L-phenylalanine Methyl Ester

Using the general procedure described in example 17, starting with4-amino-N-[[2-(trifluoromethyl)phenyl]thioxomethyl]-L-phenylalaninemethyl ester and 2,6-dichlorobenzoyl chloride,4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[2-(trifluoromethyl)phenyl]thioxomethyl]-L-phenylalaninemethyl ester was prepared in 98% yield as an amorphous colorless solid.HR MS: Obs. mass, 555.0511. Calcd. mass, 555.0524, (M+H).

Example 394-[[(2,6-Dichlorophenyl)carbonyl]amino]-N-[[2-(trifluoromethyl)phenyl]thioxomethyl]-L-phenylalanine

Using the general procedure described in example 18, starting with4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[2-(trifluoromethyl)phenyl]thioxomethyl]-L-phenylalanine methyl ester,4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[2-(trifluoromethyl)phenyl]thioxomethyl]-L-phenylalaninewas prepared in 99% yield as an amorphous colorless solid. HR MS: Obs.mass, 541.0358. Calcd. mass, 541.0367, (M+H).

Example 40 1-(4-Bromobutyl)cyclopentanecarboxylic Acid Methyl Ester

To a solution of diisopropylamine (150 mmol, 21 mL) in THF (100 mL) at−10° C. was added dropwise a 2.5M solution of n-butyl lithium in hexanes(145 mmol, 58 mL) while maintaining the temperature below 0° C. Afterthe addition was complete, the solution was stirred for 30 min at 0° C.,then it was cooled to −70° C. using a dry ice/acetone bath. A solutionof methyl cyclopentanecarboxylate (100 mmol, 13.1 g) in THF (20 mL) wasadded dropwise at −70° C. maintaining the reaction temperature between−60 to −70° C. The mixture was then stirred for 1 h at −50 to −60° C.and a solution of 1,4-dibromobutane (100 mmol, 21.59 g) in THF (20 mL)was added dropwise and the light brown suspension was stirred for 1 h at−60 to −70° C. The cooling bath was removed and the reaction was allowedto equilibrate to room temperature and stirred overnight. The reactionmixture then was poured into a saturated solution of ammonium chloride(200 mL) and the mixture was extracted with diethyl ether (2×100 mL).The combined extracts were washed with brine (150 mL), dried (MgSO₄),filtered and the solution was concentrated under reduced pressure. Theresulting residue was distilled at 120-133° C./2.5 mm Hg to obtain 12.8g (48%) of 1-(4-bromobutyl)cyclopentanecarboxylic acid methyl ester as acolorless oil. HR MS: Obs. mass, 262.0565. Calcd. mass, 262.0568, (M+).

Example 41 1-[4-(Methylthio)butyl]cyclopentanecarboxylic Acid MethylEster

To a solution of 1-(4-bromobutyl)cyclopentanecarboxylic acid methylester (38 mmol, 10 g) in DMF (100 mL) was added sodium thiomethoxide(72.6 mmol, 5.09 g). After the addition, an exothermic reaction ensuedand the mixture turned to a light brown cloudy solution. The mixture wasstirred for 15 h at room temperature, then was poured into water (200mL) and extracted with diethyl ether (2×150 mL). The combined extractswere washed with brine (150 mL), dried (MgSO₄), filtered and thesolution was concentrated in vacuo. The residual material was purifiedby silica gel column chromatography to afford 4.43 g (51%) of methyl1-[4-(methylthio)butyl]cyclopentanecarboxylic acid methyl ester as acolorless oil. HR MS: Obs. mass, 230.1343. Calcd. mass, 230.1341, (M+).

Example 42 1-[4-(Methylsulfonyl)butyl]cyclopentanecarboxylic Acid MethylEster

To a solution of 1-[4-(methylthio)butyl]cyclopentanecarboxylic acidmethyl ester (19.2 mmol, 4.43 g) in acetic acid (20 mL) was added 30%hydrogen peroxide (10 mL) and stirred mixture was heated to 70° C. for15 h. TLC analysis of the mixture indicated the absence of startingmaterial. The reaction mixture was cooled to room temperature and wasconcentrated under vacuum. The residue was poured into saturated sodiumbicarbonate solution and was extracted with diethyl ether (3×100 mL).The combined extracts were washed with brine (200 mL), dried (MgSO₄),filtered and the solvent was removed under reduced pressure. Theresidual material was purified by silica gel column chromatography toafford 4.94 g (98%) of 1-[4-(methylsulfonyl)butyl]cyclopentanecarboxylicacid methyl ester as a colorless oil. LR MS (C12H22O4S): 263 (M+H).

Example 43 1-[4-(Methylsulfonyl)butyl]cyclopentane Carboxylic Acid

To a solution of 1-[4-(methylsulfonyl)butyl]cyclopentanecarboxylic acidmethyl ester (18.8 mmol, 4.94 g) in a mixture of THF (38 mL) andmethanol (38 mL) was added 1 N sodium hydroxide (38 mL) and the mixturewas heated to 50-55° C. After 15 h, TLC analysis of the reaction mixtureindicated the absence of starting material and the mixture was allowedto cool to room temperature. The solvent was removed under vacuum andthe residue was diluted with water (100 mL) and extracted with diethylether (2×50 mL) to remove any neutral impurities. Then, the basicaqueous layer was acidified with 1 N hydrochloric acid and the productwas extracted with ethyl acetate (2×75 mL). The combined extracts werewashed with brine, dried (MgSO₄), filtered and the solution wasconcentrated in vacuo. The residual material was dried under high vacuumto afford 4.31 g (92%) of 1-[4-(methylsulfonyl)butyl]cyclopentanecarboxylic acid as a low melting colorless solid. LR MS (C11H20O4S): 249(M+H).

Example 44 1-[4-(Methylthio)butyl]cyclopentanecarboxylic Acid

To a solution of 1-[4-(methylthio)butyl]cyclopentanecarboxylic acidmethyl ester (18.8 mmol, 4.94 g) in a mixture of THF (38 mL) andmethanol (38 mL) was added 1 N sodium hydroxide (38 mL)and the mixturewas heated to 50-55° C. for 15 h. TLC analysis of the reaction mixturedid not detect the presence of starting ester and the reaction wascooled to room temperature,. The volatiles were removed under reducedpressure and the residue was diluted with water (100 mL) and wasextracted with diethyl ether (2×50 mL) to remove any neutral impurities.Then the separated aqueous layer was acidified with 1 N hydrochloricacid and the mixture was extracted with ethyl acetate (2×75 mL). Thecombined ethyl acetate extracts were washed with brine, dried (MgSO₄),filtered, then concentrated in vacuo and the residue was dried underhigh vacuum to afford 4.31 g (92%) of1-[4-(methylthio)butyl]cyclopentanecarboxylic acid as a low meltingcolorless solid. HR MS: Obs. mass, 216.1181. Calcd. mass, 216.1184, M+.

Example 45N-[[1-[4-(Methylthio)butyl]cyclopentyl]carbonyl]-4-nitro-L-phenylalanineMethyl Ester

To a suspension of 4-nitro-L-phenylalanine methyl ester hydrochloridesalt (181.84 mmol, 47.41 g),1-[4-(methylthio)butyl]cyclopentanecarboxylic acid (177.17 mmol, 38.33g) in DMF (470 mL) were added HBTU (177.17 mmol, 67.2 g) anddiisopropylethylamine (443 mmol, 77 mL) at room temperature. The clearsolution was stirred for 15 h at room temperature at which time TLCanalysis of the mixture indicated the absence of starting materials. Thereaction mixture was diluted with 600 mL of ethyl acetate then waswashed in turn with 0.5N hydrochloric acid (2×250 mL), saturated sodiumbicarbonate solution (2×250 mL) and brine (300 mL). The dried (MgSO₄)organic layer was filtered and evaporated to dryness under reducedpressure. The crude product which was purified by silica gel columnchromatography to afford 58.5 g (78%) ofN-[[1-[4-(methylthio)butyl]cyclopentyl]carbonyl]-4-nitro-L-phenylalaninemethyl ester as an amorphous colorless solid. HRMS: Obs. mass, 423.1940.Calcd. mass, 423.1953 (M+H).

Example 464-Nitro-N-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]carbonyl]-L-phenylalanineMethyl Ester

To a solution ofN-[[1-[4-(methylthio)butyl]cyclopentyl]carbonyl]-4-nitro-L-phenylalaninemethyl ester (138.4 mmol, 58.5 g) in dichloromethane (1.2 L) was addedm-chloroperbenzoic acid (415 mmol, 71.7 g) at −5° C. (ice-salt bath).The suspension was stirred for 30 min at 0° C. and allowed to warm toroom temperature. After 5 h, analysis of the reaction by TLC indicatedthat the starting material was gone. The precipitated solid was removedby filtration and the filtrate was concentrated under vacuum to afford acolorless residue. The residue was dissolved in ethyl acetate (600 mL)and was washed with saturated sodium bicarbonate solution (3×300 mL).TLC analysis showed the presence of m-chloroperbenzoic acid.Accordingly, the ethyl acetate layer was washed in turn with saturatedsodium bisulfite solution (20 g in 150 mL of water), saturated sodiumbicarbonate solution (200 mL) and brine (300 mL). The dried (MgSO₄)ethyl acetate layer was filtered and evaporated to dryness to give acrude product which was dissolved in ethyl acetate. Diethyl ether andhexane were added to precipitate an oily residue. Some of the solventwas removed under reduced pressure to obtain a white suspension. Thesuspension was further diluted with diethyl ether and the resultingsolid was collected by filtration and was washed with hexane. Thecolorless low melting solid was dried to furnish 53.9 g (86%) ofN-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]carbonyl]-4-nitro-L-phenylalaninemethyl ester, mp 40-44° C. HRMS: Obs. mass, 455.1854. Calcd. mass,455.1852 (M+H).

Example 47N-[[1-[4-(Methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-4-nitro-L-phenylalanineMethyl Ester

To a solution ofN-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]carbonyl]-4-nitro-L-phenylalaninemethyl ester (33 mmol, 15 g) in toluene (100 mL, stored over 4 Åmolecular sieves) and freshly distilled THF (50 mL) was added Lawesson'sreagent (33 mmol, 13.35 g, 1.0 equiv.) at room temperature. The solutionwas heated to 60-65° C. and was stirred for 48 h at which time TLCanalysis of the mixture indicated the absence of starting material. Thereaction mixture was cooled to room temperature and was poured intosaturated sodium bicarbonate solution (200 mL) and extracted with ethylacetate (3×150 mL). An oil formed in the aqueous layer, which wasseparated, diluted with water and extracted with ethyl acetate (2×50mL). The combined ethyl acetate extracts were washed with saturatedsodium bicarbonate solution (200 mL), with brine (300 mL), dried(MgSO₄), filtered and the solution was concentrated in vacuo. Theresidual light brown syrup was purified by silica gel columnchromatography (hexane:ethyl acetate, 1:1) to obtain 6.87 g (44%) ofN-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-4-nitro-L-phenylalaninemethyl ester as a fluffy yellow solid. HRMS: Obs. mass, 493.1438. Calcd.mass, 493.1443 (M+Na).

Example 484-Amino-N-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl)-L-phenylalanineMethyl Ester

The poorly solubleN-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-4-nitro-L-phenylalaninemethyl ester (19.3 mmol, 9.07 g) was dissolved in methanol (150 mL) andTHF (20 mL) by gentle heating with a heat gun. To this solution, zincdust (˜325 mesh, 193 mmol, 12.62 g, 10 equiv.) and ammonium chloride(289.5 mmol, 15.5 g, 15 equiv.) were added followed by water (75 mL) atroom temperature. After the addition of water, an exothermic reactionensued and the temperature rose to 45 to 50° C. The suspension wasstirred for 1 h, at which time TLC analysis of the mixture indicated theabsence of starting material. The reaction mixture was filtered and thefilter cake was washed with methanol (200 mL) and THF (100 mL). Thevolatiles were removed under vacuum and the organic residue wasextracted into ethyl acetate (2×200 mL). The combined extracts werewashed brine (250 mL) then were dried (MgSO₄), filtered and evaporatedto dryness to give 8.37 g (98%) of4-amino-N-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl)-L-phenylalaninemethyl ester as a colorless gum which was used directly for next step.HRMS: Obs. mass, 441.1884. Calcd. mass, 441.1882 (M+H).

Example 494-[[(2,6-Dichlorophenyl)carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalanineMethyl Ester

To a solution of4-amino-N-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalaninemethyl ester (19.0 mmol, 8.37 g) and 2,6-dichlorobenzoyl chloride (21mmol, 4.4 g) in dichloromethane (90 mL) was added diisopropylethylamine(32.3 mmol, 5.6 mL) at room temperature. The solution was stirred for 15h at which time TLC analysis of the mixture indicated the absence ofstarting material. Then, it was diluted with water (100 mL) and the twolayers were separated. The aqueous phase was extracted withdichloromethane (100 mL) and the combined extracts were washed withbrine (200 mL). The dried (MgSO₄) solution was concentrated under vacuumand the residue was purified by silica gel column chromatography elutingwith (hexane:ethyl acetate:dichloromethane, 1:1:1) to obtain 11.54 g(99%) of4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalaninemethyl ester as a colorless solid, mp 200-202° C. HRMS: Obs. mass,613.1367. Calcd. mass, 613.1363 (M+H).

Example 504-[[(2,6-Dichlorophenyl)carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalanine

To a solution of4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalaninemethyl ester (25.86 mmol, 15.87 g) in ethanol (75 mL) was added aqueous1.0N sodium hydroxide (60 mL) at 50° C. The mixture was heated to 50-55°C. and the resulting clear light brown solution was stirred for 22 h atwhich time TLC analysis of the mixture indicated the absence of startingmaterial. The mixture was diluted with water and allowed to cool to roomtemperature and was filtered to remove a small amount of solids. Thefiltrate was concentrated and the residual aqueous solution was washedwith diethyl ether (2×75 mL). The basic aqueous layer was acidified with3.0N HCl to form a cloudy suspension and was extracted with ethylacetate (3×100 mL). The combined ethyl acetate extracts were washed withbrine (200 mL) then the dried (MgSO₄) solution was filtered andevaporated to dryness. The residue was taken up in dichloromethane anddiluted with diethyl ether:hexane (1:1) to obtain a solid which wascollected by filtration. Trituration of the solid with hot ethyl acetate(˜100 mL) resulted in a suspension that was then diluted with diethylether (˜50 mL) and the solid was collected by filtration. The aboveTrituration was repeated to afford 10.89 g (70%) of4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalanineas a colorless solid. HR MS: Obs. mass, 599.1193. Calcd. mass, 599.1208(M+H).

Example 514-[[(2,6-Dichlorophenyl)carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalanineSodium Salt

A suspension of4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalanine(16.49 mmol, 9.89 g) in water (100 mL) was treated with aqueous 1.0Nsodium hydroxide (16.4 mmol, 16.4 mL) at room temperature. The mixturewas heated to 40-45° C. and some acetonitrile (˜15 mL) was added to givean essentially clear solution containing a small amount of suspendedsolid. The solution was filtered and the filtrate was lyophilized toafford 10.1 g of sodium salt as a colorless solid. HRMS: Obs. mass,621.1023. Calcd. mass, 621.1027 (M+H).

Example 524-[[(2,4-Dimethylpyridin-3-yl)carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalanineMethyl Ester

To an ice cold solution of 2,4-dimethyl-3-pyridinecarboxylic acid (0.3mmol, 45 mg) in dichloromethane (2 mL) containing one drop of DMF, wasadded oxalyl chloride (0.39 mmol, 49.5 mg) at 0° C. The reaction mixturewas stirred for 30 min at this temperature, was allowed to warm to roomtemperature and was stirred for an additional 2 h. The solution wasconcentrated and the residue was dried under high vacuum. To a mixtureof above acid chloride and4-amino-N-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalaninemethyl ester (0.2 mmol, 88 mg) in dichloromethane (3 mL) was addeddiisopropylethylamine (1 mmol, 0.175 mL) at room temperature. After thesolution had stirred for 15 h, TLC analysis of the mixture did notdetect any starting material remaining. The solution was diluted withwater (20 mL) and dichloromethane (20 mL) and the layers were separated.The aqueous phase was extracted with dichloromethane (10 mL) and thecombined organic extracts were washed with brine (300 mL). The dried(MgSO₄) solution was filtered and evaporated to dryness and the residualmaterial was purified by RP-HPLC to obtain 74 mg (65%) of4-[[(2,4-dimethylpyridin-3-yl)carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalaninemethyl ester as an amorphous colorless solid. HRMS: Obs. mass, 574.2389.Calcd. mass, 574.2409 (M+H).

Example 534-[[(2,4-Dimethylpyridin-3-yl)carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalanineTrifluoroacetic Acid Salt

To a solution of4-[[(2,4-dimethylpyridin-3-yl)carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalaninemethyl ester (0.118 mmol, 68 mg) in ethanol (4 mL) was added aqueous1.0N sodium hydroxide (3 mL) at room temperature and the stirred mixturewas heated to 45-50° C. After 3 h TLC analysis of the clear solutionindicated that the starting material had been consumed. The mixture wasconcentrated and the crude residue was purified by RP-HPLC to afford54.5 mg (82%) of4-[[(2,4-dimethylpyridin-3-yl)carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalaninetrifluoroacetic acid salt as an amorphous colorless solid. HR MS: Obs.mass, 560.2240. Calcd. mass, 560.2253 (M+H).

Example 54 1-(4-Bromobutyl)cyclobutanecarboxylic Acid Ethyl Ester

Using the general procedure described in example 40, starting withcyclobutanecarboxylic acid ethyl ester,1-(4-bromobutyl)cyclobutanecarboxylic acid ethyl ester was prepared in58% yield as a colorless oil. HR MS: Obs. mass, 263.0563. Calcd. mass,263.0568, M+.

Example 55 1-[4-(Methylthio)butyl]cyclobutanecarboxylic Acid Ethyl Ester

Using the general procedure described in example 41, starting with1-(4-bromobutyl)cyclobutanecarboxylic acid ethyl ester,1-[4-(methylthio)butyl]cyclobutanecarboxylic acid ethyl ester wasprepared in 87% yield as a colorless oil. HR MS: Obs. mass, 230.1339.Calcd. mass, 230.1340, M+.

Example 56 Ethyl 1-[4-(Methylsulfonyl)butyl]cyclobutane Carboxylic AcidEthyl Ester

Using the general procedure described in example 46, starting with1-[4-(methylthio)butyl]cyclobutanecarboxylic acid ethyl ester,1-[4-(methylsulfonyl)butyl]cyclobutanecarboxylic acid ethyl ester wasprepared in 92% yield as a colorless oil. HR MS: Obs. mass, 262.1231.Calcd. mass, 262.1238, M+.

Example 57 1-[4-(Methylsulfonyl)butyl]cyclobutanecarboxylic Acid

Using the general procedure described in example 43, starting with1-[4-(methylsulfonyl)butyl]cyclobutanecarboxylic acid ethyl ester,1-[4-(methylsulfonyl)butyl]cyclobutanecarboxylic acid was prepared in92% yield as a low melting colorless solid. HR MS: Obs. mass, 234.0921.Calcd. mass, 234.0918, (M+).

Example 58N-[[1-[4-(Methylsulfonyl)butyl]cyclobutyl]carbonyl]-4-nitro-L-phenylalanineMethyl Ester

Using the general procedure described in example 45, starting with1-[4-(methylsulfonyl)butyl]cyclobutanecarboxylic acid and4-nitro-L-phenylalanine methyl ester hydrochloride salt,N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]carbonyl]-4-nitro-L-phenylalaninemethyl ester was prepared in 89% yield as a yellow gum. HR MS: Obs.mass, 441.1700. Calcd. mass, 441.1696 (M+H).

Example 59N-[[1-[4-(Methylsulfonyl)butyl]cyclobutyl]thioxomethyl)-4-nitro-L-phenylalanineMethyl Ester

Using the general procedure described in example 47, starting with4-nitro-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]carbonyl]-L-phenylalaninemethyl ester,N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl)-4-nitro-L-phenylalaninemethyl ester was prepared in 80% yield as a colorless solid, mp 150-152°C. HR MS: Obs. mass, 457.1464. Calcd. mass, 457.1467, (M+H).

Example 604-Amino-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl)-L-phenylalanineMethyl Ester

Using the general procedure described in example 48, starting withN-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl)-4-nitro-L-phenylalaninemethyl ester,4-amino-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl)-L-phenylalaninemethyl ester was prepared in 94% yield as a hygroscopic solid. HR MS:Obs. mass, 427.1720. Calcd. mass, 427.1725, (M+H).

Example 614-[[(2,6-Dichlorophenyl)carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalanineMethyl Ester

Using the procedure described in example 49, starting with4-amino-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl)-L-phenylalaninemethyl ester,4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalaninemethyl ester was obtained in 92% yield as an amorphous colorless solid.HR MS: Obs. mass, 599.1207. Calcd. mass, 599.1208 (M+H).

Example 624-[[(2,6-Dichlorophenyl)carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalanine

Using the general procedure described in example 50, starting with4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalaninemethyl ester,4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalaninewas prepared in 99% yield as an amorphous colorless solid. HR MS: Obs.mass, 585.1038. Calcd. mass, 585.1051 (M+H).

Example 63N-[[1-[4-(Methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-4-[[[4-(trifluoromethyl)pyrimidin-5-yl]carbonyl]amino]-L-phenylalanine Methyl Ester

Using the general procedure described in example 45, starting with4-(trifluoromethyl)pyrimidine-5-carboxylic acid and4-amino-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl)-L-phenylalaninemethyl ester,N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-4-[[[2-(trifluoromethyl)pyrimidin-5-yl]carbonyl]amino]-L-phenylalanine methyl ester was preparedin 32% yield as an amorphous colorless solid. HR MS: Obs. mass,601.1766. Calcd. mass, 601.1766 (M+H).

Example 64N-[[1-[4-(Methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-4-[[[2-(trifluoromethyl)pyrimidin-5-yl]carbonyl]amino]-L-phenylalanine

Using the general procedure described in example 50, starting withN-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-4-[[[2-(trifluoromethyl)pyrimidin-5-yl]carbonyl]amino]-L-phenylalanine methyl ester,N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-4-[[[2-(trifluoromethyl)pyrimidin-5-yl]carbonyl]amino]-L-phenylalanine was prepared in 22% yieldas an amorphous colorless solid. HR MS: Obs. mass, 587.1619. Calcd.mass, 587.1609 (M+H).

Example 65 Preparation 1-(3-Bromopropyl)cyclobutanecarboxylic Acid EthylEster

Using the general procedure described in example 40, starting withcyclobutanecarboxylic acid ethyl ester and 1,3-dibromopropane,1-(3-bromopropyl)cyclobutanecarboxylic acid ethyl ester was prepared in33% yield as a colorless oil. HR MS: Obs. mass, 248.0416. Calcd. mass,248.0412 (M+).

Example 66 1-[3-(Methylthio)propyl]cyclobutanecarboxylic Acid EthylEster and 1-[3-(Methylthio)propyl]cyclobutanecarboxylic Acid

Using the general procedure described in example 41, starting with1-(3-bromopropyl)cyclobutanecarboxylic acid ethyl ester,1-[3-(methylthio)propyl]cyclobutanecarboxylic acid ethyl ester wasprepared in 58% yield as a colorless oil. HR MS: Obs. mass, 216.1182.Calcd. mass, 216.1184 (M+). Also,1-[3-(methylthio)propyl]cyclobutanecarboxylic acid was obtained in 16%yield as a colorless oil. HR MS: Obs. mass, 188.0872. Calcd. mass,188.0871 (M+).

Example 67N-[[1-[3-(Methylthio)propyl]cyclobutyl]carbonyl]-4-nitro-L-phenylalanineMethyl Ester

Using the general procedure described in example 45, starting with4-nitro-L-phenylalanine methyl ester hydrochloride salt and1-[3-(methylthio)propyl]cyclobutanecarboxylic acid,N-[[1-[3-(methylthio)propyl]cyclobutyl]carbonyl]-4-nitro-L-phenylalaninemethyl ester was prepared in 92% yield as an yellow viscous oil. HR MS:Obs. mass, 395.1638. Calcd. mass, 395.1640 (M+H).

Example 68N-[[1-[3-(Methylthio)propyl]cyclobutyl]thioxomethyl]-4-nitro-L-phenylalanineMethyl Ester

Using the general procedure described in example 47, starting with4-nitro-N-[[1-[3-(methylthio)propyl]cyclobutyl]carbonyl]-4-nitro-L-phenylalaninemethyl ester,N-[[1-[3-(methylthio)propyl]cyclobutyl]thioxomethyl]-4-nitro-L-phenylalaninemethyl ester was prepared in 95% yield as a colorless viscous oil. HRMS: Obs. mass, 411.1408. Calcd. mass, 411.1412 (M+H).

Example 694-Amino-N-[[1-[3-(methylthio)propyl]cyclobutyl]thioxomethyl]-L-phenylalanineMethyl Ester

Using the general procedure described in example 48, starting withN-[[1-[3-(methylthio)propyl]cyclobutyl]thioxomethyl]-4-nitro-L-phenylalanine methyl ester,4-amino-N-[[1-[3-(methylthio)propyl]cyclobutyl]thioxomethyl]-L-phenylalaninemethyl ester was prepared in 97% yield as an hygroscopic yellow solid.HR MS: Obs. mass, 381.1660. Calcd. mass, 381.1671 (M+H).

Example 704-[(2,6-Dichlorophenylcarbonyl)amino]-N-[[1-[3-(methylthio)propyl]cyclobutyl]thioxomethyl]-L-phenylalanineMethyl Ester

Using the general procedure described in example 49, starting with4-(amino)-N-[[1-[3-(methylthio)propyl]cyclobutyl]thioxomethyl]-L-phenylalaninemethyl ester and 2,6-dichlorobenzoyl chloride,4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[1-[3-(methylthio)propyl]cyclobutyl]thioxomethyl]-L-phenylalaninemethyl ester was prepared in 83% yield as a colorless solid, mp 184-186°C. HR MS: Obs. mass, 553.1139. Calcd. mass, 553.1153 (M+H).

Example 714-[[(2,6-Dichlorophenyl)carbonyl]amino]-N-[[1-[3-(methylthio)propyl]cyclobutyl]thioxomethyl]-L-phenylalanine

Using the general procedure described in example 50, starting with4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[1-[3-(methylthio)propyl]cyclobutyl]thioxomethyl]-L-phenylalaninemethyl ester,4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[1-[3-(methylthio)propyl]cyclobutyl]thioxomethyl]-L-phenylalaninewas prepared in 97% yield as a colorless solid, mp 186-188° C. HR MS:Obs. mass, 539.0986. Calcd. mass, 539.0996 (M+H).

Example 72 1-[3-(Methylsulfonyl)propyl]cyclobutanecarboxylic Acid EthylEster

Using the general procedure described in example 46, starting with1-[3-(methylthio)propyl]cyclobutanecarboxylic acid ethyl ester,1-[3-(methylsulfonyl)propyl]cyclobutanecarboxylic acid ethyl ester wasprepared in 87% yield as a colorless oil. HR MS: Obs. mass, 248.1084.Calcd. mass, 248.1082 (M+).

Example 73 1-[3-(Methylsulfonyl)propyl]cyclobutanecarboxylic Acid

Using the general procedure described in example 43, starting with1-[3-(methylsulfonyl)propyl]cyclobutanecarboxylic acid ethyl ester,1-[3-(methylsulfonyl)propyl]cyclobutanecarboxylic acid was prepared in76% yield as a colorless solid, mp 113-116° C. HR MS: Obs. mass,220.0770. Calcd. mass, 220.0769 (M+).

Example 74N-[[1-[3-(Methylsulfonyl)propyl]cyclobutyl]carbonyl]-4-nitro-L-phenylalanineMethyl Ester

Using the general procedure described in example 45, starting from4-nitro-L-phenylalanine methyl ester and1-[3-(methylsulfonyl)propyl]cyclobutane carboxylic acid,N-[[1-[3-(methylsulfonyl)propyl]cyclobutyl]carbonyl]-4-nitro-L-phenylalanine methyl ester wasprepared in 76% yield as a colorless amorphous solid. HR MS: Obs. mass,427.1526. Calcd. mass, 427.1539 (M+H).

Example 75N-[[1-[3-(Methylsulfonyl)propyl]cyclobutyl]thioxomethyl]-4-nitro-L-phenylalanineMethyl Ester

Using the general procedure described in example 47, starting withN-[[1-[3-(methylsulfonyl)propyl]cyclobutyl]carbonyl]-4-nitro-L-phenylalaninemethyl ester,N-[[1-[3-(methylsulfonyl)propyl]cyclobutyl]thioxomethyl]-4-nitro-L-phenylalaninemethyl ester was prepared in 88% yield as an yellow sticky solid. HR MS:Obs. mass, 443.1309. Calcd. mass, 443.1310 (M+H).

Example 764-Amino-N-[[1-[3-(methylsulfonyl)propyl]cyclobutyl]thioxomethyl]-L-phenylalanineMethyl Ester

Using the general procedure described in example 48, starting withN-[[1-[3-(methylsulfonyl)propyl]cyclobutyl]thioxomethyl]-4-nitro-L-methylester,4-amino-N-[[1-[3-(methylsulfonyl)propyl]cyclobutyl]thioxomethyl]-L-phenylalaninemethyl ester was prepared in 97% yield as an hygroscopic yellow solid.HR MS: Obs. mass, 413.1556. Calcd. mass, 413.1570 (M+H).

Example 774-[[(2,6-Dichlorophenyl)carbonyl]amino]-N-[[1-[3-(methylsulfonyl)propyl]cyclobutyl]thioxomethyl]-L-phenylalanineMethyl Ester

Using the general procedure described in example 49, starting with4-amino-N-[[1-[3-(methylsulfonyl)propyl]cyclobutyl]thioxomethyl]-L-phenylalaninemethyl ester and 2,6-dichlorobenzoyl chloride,4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[1-[3-(methylsulfonyl)propyl]cyclobutyl]thioxomethyl]-L-phenylalaninemethyl ester was prepared in 82% yield as a colorless amorphous solid.HR MS: Obs. mass, 585.1056. Calcd. mass, 585.1051 (M+H).

Example 784-[[(2,6-Dichlorophenyl)carbonyl]amino]-N-[[1-[3-(methylsulfonyl)propyl]cyclobutyl]thioxomethyl]-L-phenylalanine

Using the general procedure described in example 50, starting with4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[[1-[3-(methylsulfonyl)propyl]cyclobutyl]thioxomethyl]-L-phenylalaninemethyl ester,4-[(2,6-dichlorophenylcarbonyl)amino]-N-[[1-[3-(methylsulfonyl)propyl]cyclobutyl]thioxomethyl]-L-phenylalaninewas prepared in 87% yield as an amorphous colorless solid. HR MS: Obs.mass, 571.0894. Calcd. mass, 571.0895 (M+H).

Example 79 2-Chloro-5-(trifluoromethyl)phenol Triflate

To a solution of 2-chloro-5-(trifluoromethyl)phenol (24.4 mmol, 4.8 g)in dichloromethane (160 mL) was added DMAP (54.0 mmol, 6.7 g) at −70° C.followed by triflic anhydride (36.6 mmol, 10.32 g, 6.16 mL) at −70° C.After the addition was complete, the suspension was stirred for 30 minat this temperature and then warmed to room temperature. After another 3h, when starting material could not be detected by TLC of the reactionmixture indicated the absence of starting material, the stirred mixturewas diluted with H₂O (100 mL) and the two layers were separated.

The aqueous layer was extracted with dichloromethane (100 mL) and thenthe combined dichloromethane extracts were washed with brine. The dried(MgSO₄) solution was filtered and evaporated to dryness to give acolorless residue which was purified by silica gel column chromatography(hexane:diethyl ether 4:1) to obtain 6.8 g (85%) of2-chloro-5-(trifluoromethyl)phenol triflate as a colorless oil HR MS:Obs. mass, 327.9388. Calcd. mass, 327.9392 (M+).

Example 80 2-Chloro-5-(trifluoromethyl)benzoic Acid

A 250 mL pressure bottle was charged with2-chloro-5-(trifluoromethyl)phenol triflate (20.6 mmol, 6.76 g),Pd(OAc)₂ (1.71 mmol, 384 mg) and dppp (1.71 mmol, 701 mg). The flask wasclosed with a septum and evacuated three times with argon. Acetonitrile(114 mL), triethylamine (225.3 mmol, 30.7 mL) and water (22.2 mL) wereadded in succession with the aid of a syringe. The rubber septum wasreplaced with a teflon lined lid. The flask was pressurized with carbonmonoxide (40 psi) and the gas was released. This process was repeatedthree times and finally the reaction was stirred for 5 min underpressure. The flask was then disconnected from the gas cylinder,immersed in a preheated oil bath (83-85° C.) and stirred for 2 h. Theflask was re-pressurized with carbon monoxide and stirred for another 1h. After the reaction mixture was cooled to room temperature, thepressure was released and it diluted with diethyl ether (250 mL) and 25mL of 1.0 N NaOH. The sodium salt was extracted into water (2×100 mL).The combined aqueous extracts were acidified with 1.0 N HCl andextracted with diethyl ether (3×100 mL). The combined diethyl etherextracts were washed with brine, dried (MgSO₄), filtered and thesolution was concentrated in vacuo to furnish a light yellow solid. Thesolid was dissolved in diethyl ether (100 mL) and extracted with 1.0 NNaOH solution (2×50 mL). The combined aqueous layers were acidified andextracted with diethyl ether (2×100 mL). After the combined organicextracts were washed with brine (100 mL), the dried (MgSO₄) solution wasfiltered and evaporated to dryness to give 1.6 g (35%) of2-chloro-5-(trifluoromethyl)benzoic acid obtained as a colorless solid,mp 82-83.5° C. HR MS: Obs. mass, 223.9852. Calcd. mass, 223.9851 (M+).

Example 814-[[[(2-Chloro-5-(trifluoromethyl)phenyl]carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl[-L-phenylalanineMethyl Ester

Using the general procedure described in example 52, starting with4-amino-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalaninemethyl ester and 2-chloro-5-(trifluoromethyl)benzoic acid,4-[[[(2-chloro-5-(trifluoromethyl)phenyl]carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalaninemethyl ester was prepared in 97% yield as a colorless amorphous solid.HR MS: Obs. mass, 633.1477. Calcd. mass, 633.1471 (M+H).

Example 824-[[[(2-Chloro-5-(trifluoromethyl)phenyl]carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalanine

Using the general procedure described in example 50, starting with4-[[[(2-chloro-5-(trifluoromethyl)phenyl]carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalaninemethyl ester,4-[[[(2-chloro-5-(trifluoromethyl)phenyl]carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalaninewas prepared in 75% yield as an amorphous colorless solid. HR MS: Obs.mass, 619.1315. Calcd. mass, 619.1318 (M+H).

Example 834-[[[(2,6-Dimethyl-4-(trifluoromethyl)pyridin-3-yl]carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalanineMethyl Ester

To suspension of 2,6-dimethyl-4-(trifluoromethyl)pyridine-3-carboxylicacid (0.84 mmol, 184 mg) in dichloromethane (10 mL) containing DMF (3drops) was added dropwise oxalyl chloride (1.14 mmol, 146 mg, 0.1 mL) at0° C. for 2-3 min. After the addition was complete, the reaction wasstirred for 30 min at 0° C. and then allowed to warm to roomtemperature. The clear solution was stirred for another 2 h at roomtemperature, then the solvent was removed under reduced pressure and theresidue was dried under high vacuum for 1 h. To a mixture of4-amino-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalaninemethyl ester (0.7 mmol, 298 mg) and amberlyst A-21 (1.4 mmol, 900 mg) inethyl acetate (10 mL, stored over 4 Å molecular sieves) in a 4-neckedsonicator flask was added a solution of the above prepared acid chloridein ethyl acetate (6 mL) at room temperature. The mixture was subjectedfor sonication for 30 min and then was partitioned between water (100mL) and ethyl acetate (100 mL). The separated aqueous layer wasextracted with ethyl acetate (50 mL) and the combined extracts werewashed brine (100 mL. The dried (MgSO₄) ethyl acetate layer was filteredand evaporated to dryness in vacuo and the residue was purified byRP-HPLC to obtain 139 mg (32%) of4-[[[(2,6-dimethyl-4-(trifluoromethyl)pyridin-3-yl]carbonyl]amino]-N-[[-1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalaninemethyl ester as an amorphous colorless solid. HR MS: Obs. mass,628.2122. Calcd. mass, 628.2127 (M+H).

Example 844-[[[(2,6-Dimethyl-4-(trifluoromethyl)pyridin-3-yl]carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalanine

To a suspension of4-[[[(2,6-dimethyl-4-(trifluoromethyl)pyridin-3-yl]carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalaninemethyl ester (0.2 mmol, 125 mg) in ethanol (7 mL) was added a 1.0Nsolution of sodium hydroxide (5.0 mL) at room temperature. Within fewminutes the reaction mixture become a clear solution and it was heatedto 45-50° C. and stirred for 4 hr, at which time TLC analysis of themixture indicated the absence of starting material. After the solutionwas cooled to room temperature, the ethanol was removed in vacuo and theresidue was purified by RP-HPLC to obtain 67.5 mg (55%) of4[[[(2,6-dimethyl-4-(trifluoromethyl)pyridin-3-yl]carbonyl]amino]-N-[[1-[4-(methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalaninemethyl ester as an amorphous colorless solid. HR MS: Obs. mass,614.1970. Calcd. mass, 614.1970 (M+H).

Example 854-[[(2,6-Dichlorophenyl)carbonyl]amino]-N-[(2-bromophenyl)thioxomethyl]-L-phenylalanine

Using the method described in examples 35 to 39, and starting with2-bromobenzoic acid and 4-nitro-L-phenylalanine methyl esterhydrochloride salt, the title compound was prepared. HRMS Obs. mass,550.9593. Calcd mass, 550.9598 (M+H).

Example 864-[(2S,4R)-3-Acetyl-5-oxo-2-phenyl-4-(phenylmethyl)imidazolidin-1-yl]-N-[[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalanineand4-[(2R,4R)-3-Acetyl-5-oxo-2-phenyl-4-(phenylmethyl)imidazolidin-1-yl]-N-[[4-(methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalanine

Using the procedure described in examples 26 to 29, the title compoundswere prepared. The isomers were separated by chromatography at themethyl ester stage. For the 2S,4R isomer, HRMS, Obs. mass, 650.2670.Calcd mass, 650.2665 (M+Na). For the 2R,4R isomer, HRMS, obs. mass,650.2679. Calcd. mass, 650.2665 (M+Na).

Assays

1. VLA-4/VCAM-1 Screening Assay

VLA-4 antagonist activity, defined as ability to compete for binding toimmobilized VCAM-1, was quantitated using a solid-phase, dual antibodyELISA. VLA-4 (α4β1 integrin) bound to VCAM-1 is detected by a complex ofanti-integrin β1 antibody: HRP-conjugated anti-mouse IgG: chromogenicsubstrate (K-Blue). Initially, this entailed coating 96 well plates(Nunc Maxisorp) with recombinant human VCAM-1 (0.4 μg in 100 μl PBS),sealing each plate and then allowing the plates to stand at 4° C. for 18hr. The VCAM-coated plates were subsequently blocked with 250 μl of 1%BSA/0.02% NaN₃ to reduce non-specific binding. On the day of assay, allplates are washed twice with VCAM Assay Buffer (200 μl/well of 50 mMTris-HCl, 100 MM NaCl, 1 mM MnCl₂, 0.05% Tween 20; pH 7.4). Testcompounds are dissolved in 100% DMSO and then diluted 1:20 in VCAM AssayBuffer supplemented with 1 mg/mL BSA (i.e., final DMSO=5%). A series of1:4 dilutions are performed to achieve a concentration range of 0.005mM-1.563 μM for each test compound. 100 μl per well of each dilution isadded to the VCAM-coated plates, followed by 10 μl of Ramos cell-derivedVLA-4. These plates are sequentially mixed on a platform shaker for 1min, incubated for 2 hr at 37° C., and then washed four times with 200μl/well VCAM Assay Buffer. 100 μl of mouse anti-human integrin β1antibody is added to each well (0.6 μg/mL in VCAM Assay Buffer+1 mg/mLBSA) and allowed to incubate for 1 hr at 37° C. At the conclusion ofthis incubation period, all plates are washed four times with VCAM AssayBuffer (200 μl/well). A corresponding second antibody, HRP-conjugatedgoat anti-mouse IgG (100 μl per well @ 1:800 dilution in VCAM AssayBuffer+1 mg/mL BSA), is then added to each well, followed by a 1 hrincubation at room temperature and concluded by three washes (200μl/well) with VCAM Assay Buffer. Color development is initiated byaddition of 100 μl K-Blue per well (15 min incubation, room temp) andterminated by addition of 100 μl Red Stop Buffer per well. All platesare then read in a UV/Vis spectrophotometer at 650 nM. Results arecalculated as % inhibition of total binding (i.e., VLA-4+VCAM-1 in theabsence of test compound). Selected data for compounds of this inventionare shown in the table below:

2. Ramos (VLA-4)/VCAM-1 Cell-Based Screening Assay Protocol

Materials

Soluble recombinant human VCAM-1 (mixture of 5- and 7-Ig domain) waspurified from CHO cell culture media by immunoaffinity chromatographyand maintained in a solution containing 0.1 M Tris-glycine (pH 7.5), 0.1M NaCl, 5 mM EDTA, 1 mM PMSF, 0.02% 0.02% NaN₃ and 10 μg/mL leupeptin.Calcein-AM was purchased from Molecular Probes Inc.

Methods

VLA-4 (α4β1 integrin) antagonist activity, defined as ability to competewith cell-surface VLA-4 for binding to immobilized VCAM-1, wasquantitated using a Ramos-VCAM-1 cell adhesion assay. Ramos cellsbearing cell-surface VLA-4, were labeled with a fluorescent dye(Calcein-AM) and allowed to bind VCAM-1 in the presence or absence oftest compounds. A reduction in fluorescence intensity associated withadherent cells (% inhibition) reflected competitive inhibition of VLA-4mediated cell adhesion by the test compound.

Initially, this entailed coating 96 well plates (Nunc Maxisorp) withrecombinant human VCAM-1 (100 ng in 100 μl PBS), sealing each plate andallowing the plates to stand at 4° C. for 18 hr. The VCAM-coated plateswere subsequently washed twice with 0.05% Tween-20 in PBS, and thenblocked for 1 hr (room temperature) with 200 μl of Blocking Buffer (1%BSA/0.02% thimerosal) to reduce non-specific binding. Following theincubation with Blocking Buffer, plates were inverted, blotted and theremaining buffer aspirated. Each plate was then washed with 300 μl PBS,inverted and the remaining PBS aspirated.

Test compounds were dissolved in 100% DMSO and then diluted 1:25 in VCAMCell Adhesion Assay Buffer (4 mM CaCl₂, 4 mM MgCl₂ in 50 mM TRIS-HCl, pH7.5) (final DMSO=4%). A series of eight 1:4 dilutions were performed foreach compound (general concentration range of 1 nM-12,500 nM). 100μl/well of each dilution was added to the VCAM-coated plates, followedby 100 μl of Ramos cells (200,000 cells/well in 1% BSA/PBS). Platescontaining test compounds and Ramos cells were allowed to incubate for45 min at room temperature, after which 165 μl/well PBS was added.Plates were inverted to remove non-adherent cells, blotted and 300μl/well PBS added. Plates were again inverted, blotted and the remainingbuffer gently aspirated. 100 μl Lysis Buffer (0.1% SDS in 50 mMTRIS-HCl, pH 8.5) was added to each well and agitated for 2 min on arotary shaking platform. The plates were then read for fluorescenceintensity on a Cytofluor 2300 (Millipore) fluorescence measurementsystem (excitation=485 nm, emission=530 nm). The results are shown inthe following table:

3. MadCAM RPMI 8866 Cell Based Assay

MadCAM binding activity was quantified using an RPMI 8866 cell-basedassay. RPMI 8866 cells bearing cell surface MadCAM were labelled withfluorescent dye (calcein AM) and allowed to bind MadCAM in the presenceor absence of test compounds. A reduction in fluoresence intensityassociated with adherent cells (% inhibition) reflects competitiveinhibition of MadCAM mediated cell adhesion by the test compound.

Initially, this entailed coating 96 well plates (Nunc F96 Maxisorp) with25 ng/well of MadCAM (100 μl/well in coating buffer: 10 mMcarbonate/bicarbonate buffer, 0.8 g/L sodium carbonate, 1.55 g/L sodiumbicarbonate, adjusted to pH 9.6 with 1N HCL), sealing and wrapping eachplate and refrigerating the plates for at least 24 hrs. TheMadCAM-coated plates were subsequently washed twice with 0.05% Tween-20in PBS, and then blocked for at least 1 hr. at room temperature with ofblocking buffer (1% nonfat dry milk in PBS) to reduce non-specificbinding. Following the incubation with blocking buffer, plates werewashed with PBS, hand blotted, and the remaining liquid aspirated.

RPMI 8866 cells (2×10⁶ cells/ml×10 ml. per plate×number of plates) weretransferred to a 50 ml centrifuge tube filled with PBS and spun at 200×gfor 8 minutes, after which the PBS is poured off and the pelletresuspended to 10×10⁶ cells/ml in PBS. Calcein (diluted with 200 μl DMSOfrom a 5 mg/ml frozen stock) was added to the cells at 5 μl/ml PBS.After incubation at 37 degrees C. for 30 min. in the dark, the cellswere washed in PBS and resuspended at 2×106 cells/ml in cell buffer(RPMI 1640 medium (no additives)).

Test compounds were dissolved in 100% DMSO and then diluted 1:25 inbinding buffer (1.5 mM CaCl₂, 0.5 mM MnCl₂ in 50 mM TRIS-HCl, adjustedto pH 7.5 with NaOH). Remaining dilutions were into dilution buffer (4%DMSO in binding buffer—2% DMSO final when diluted 1:2 in wells). Aseries of dilutions were performed for each compound tested. 129 μl ofbinding buffer was placed in the first row of wells in the MadCAM-coatedplates. 100 μl/well of dilution buffer was added to the remaining wells,followed by 5.4 μl of each test compound in the appropriate dilution (intriplicate). 100 μl of cells (200,000 cells/well) were added. Controlwells contained 100 μl dilution buffer+100 μl cell buffer, and 100 μldilution buffer+100 μl cell buffer. Plates were allowed to incubate for45 min at room temperature, after which 150 μl/well PBS was added.Plates were inverted to remove non-adherent cells, blotted and 200μl/well PBS added. Plates were again inverted, blotted and the remainingbuffer gently aspirated. 100 μl PBS was added to each well. The plateswere then read for fluorescence intensity on a fluorescence measurementsystem (excitation=485 nm, emission=530 nm, sensitivity=2). A linearrecession analysis was performed to obtain the IC₅₀ of each compound.The results are shown in following table:

ELISA IC₅₀ nM Ramos Example (VLA/VCAM) IC₅₀ RPMI IC₅₀ 3 4.0 66.5 10 1.533 11 5.6 42.5 18 0.47 60 25 6.0 101 29 220 34 4,180 39 784 50 30 53 14862 8 8.7 64 87 71 926 78 341 82 84 5.5 83

Example 4. Acute airway inflammation in the atopic primate.

Airway inflammation in the monkey was determined using a modification ofthe protocol described by Turner et al. (Turner et al., 1994). Adultmale cynomolgus monkeys (Macaca fascicularis, Hazelton Labs, Denver,Pa.) weighing between 3.6-5.8 kg were used in these studies. All animalsexhibited positive skin and airway responses to Ascaris suum antigen andhad at least a 3-fold increase in the sensitivity to methacholine (MCh)when subjected to an aerosol of ascaris extract.

On the day of each experiment the animals were anesthetized withketamine hydrochloride, 12 mg/kg, and xylazine, 0.5 mg/kg, intubatedwith a cuffed endotracheal tube (3 mm, Mallinckrodt Medical, St. Louis,Mo.), then seated in an upright position in a specially designedPlexiglass chair (Plas-Labs, Lansing, Mich.). The endotracheal tube wasconnected to a heated Fleisch pneumotachograph. Airflow was measured viaa Validyn differential pressure transducer (DP 45-24) that was attachedto the pneumotachograph. Transpulmonary pressure was measured via asecond Validyne transducer (DP 45-24) connected between a sidearm of thetracheal cannula and a 18-gauge intrapleural needle inserted in theintercostal space located below the left nipple. Recordings of pressureand flow and the calculation of R_(L) were made using the ModularInstruments data acquisition system as described above. Baseline R_(L)was measured for all animals on the day of each experiment and had anaverage value of about 0.04 cmH₂O/ml/sec.

Protocol

Airway inflammation was induced by exposing the animal to an aerosol ofA. Suum extract for 60 sec. The aerosol was delivered via a nebulizer(De Vilbiss Model 5000, Healt Care Inc., Somerset, Pa.) that wasattached to the endotracheal tube. The concentration of extract waspredetermined for each animal (500 to 50,000 PNU) and caused at least adoubling in the airway resistance. At 24 hour after the antigenchallenge, the animals were anesthetized as described previously andplaced on a stainless steel table. Airway inflammation was assessed byinserting a pediatric bronchoscope into the airway lumen down to aboutthe 4 or 5^(th) generation bronchi and gently ravaging with 3×2 mlaliquots of sterile Hanks Balanced Salt Solution. The recovered lavagefluid then was analyzed for the total cell and differential cell countsusing standard hematological techniques.

Drug Treatment

The animals received drug or a vehicle, p.o., administered 2 hours priorto antigen challenge. The compound of example 1 caused a significantdecrease in the number and percent of inflammatory cells present in thelavage fluid relative to vehicle treated control animals.

What is claimed is:
 1. A compound of the formula:

wherein X is

R₁₅ is halogen, nitro, lower alkyl sulfonyl, cyano, lower alkyl, loweralkoxy, lower alkoxycarbonyl, carboxy, lower alkyl aminosulfonyl,perfluorolower alkyl, lower alkylthio, hydroxy lower alkyl, alkoxy loweralkyl, lower alkylthio lower alkyl, lower alkylsulfinyl lower alkyl,lower alkylsulfonyl lower alkyl, lower alkylsulfinyl, lower alkanoyl,aroyl, aryl, or aryloxy; R₁₆ is hydrogen, halogen, nitro, cyano, loweralkyl, OH, perfluorolower alkyl, or lower alkylthio; wherein Het is a 5-or 6-membered heteroaromatic ring containing 1, 2 or 3 heteroatomsselected from N, O, and S, or Het is a 9- or 10-membered bicyclicheteroaromatic ring containing 1, 2, 3 or 4 heteroatoms selected from O,S, and N; R₃₀ is hydrogen or lower alkyl; and p is an integer from 0 to1; Y is the formula

R₂₂ and R₂₃ are independently hydrogen, lower alkyl, lower alkoxy,cycloalkyl, aryl, arylalkyl, nitro, cyano, lower alkylthio, loweralkylsulfinyl, lower alkyl sulfonyl, lower alkanoyl, halogen, orperfluorolower alkyl and at least one of R₂₂ and R₂₃ is other thanhydrogen, and R₂₄ is hydrogen, lower alkyl, lower alkoxy, aryl, nitro,cyano, lower alkyl sulfonyl, or halogen;  or the formula

Het is a five or six membered heteroaromatic ring bonded via a carbonatom wherein said ring contains one, two or three heteroatoms selectedfrom the group consisting of N, O and S and R₃₀ and R₃₁ areindependently hydrogen, lower alkyl, cycloalkyl, halogen, cyano,perfluoroalkyl, or aryl and at least one of R₃₀ and R₃₁ is adjacent tothe point of attachment; p is an integer of from 0 to 1;  or the formula

R₂₅ is lower alkyl, unsubstituted or fluorine substituted lower alkenyl,or a group of formula R₂₆—(CH₂)_(e)—, R₂₆ is aryl, heteroaryl, azido,cyano, hydroxy, lower alkoxy, lower alkoxycarbonyl, lower alkanoyl,lower alkylthio , lower alkyl sulfonyl, lower alkyl sulfinyl, perfluorolower alkanoyl, nitro, or R₂₆ is a group of formula —NR₂₈R₂₉; R₂₈ is Hor lower alkyl; R₂₉ is hydrogen, lower alkyl, lower alkoxycarbonyl,lower alkanoyl, aroyl, perfluoro lower alkanoylamino, lower alkylsulfonyl, lower alkylaminocarbonyl, arylaminocarbonyl, or R₂₈ and R₂₉taken together form a 4, 5 or 6-membered saturated carbacyclic ringoptionally containing one heteroatom selected from O, S, and N; with thecarbon atoms in the ring being unsubstituted or substituted by loweralkyl or halogen, Q is —(CH₂)_(f)O—, —(CH₂)_(f)S—, —(CH₂)_(f)N(R₂₇)—, or—(CH₂)_(f)—, R₂₇ is H, lower alkyl, aryl, lower alkanoyl, aroyl or loweralkoxycarbonyl, e is an integer from 0 to 4; f is an integer from 0 to3; and the dotted bond is optionally hydrogenated; or pharmaceuticallyacceptable salts or esters thereof.
 2. The compound of claim 1 whereinHet is a 5- or 6-membered monocyclic heteroaromatic ring containing 1, 2or 3 nitrogens, or a nitrogen and a sulfur, or a nitrogen and an oxygen.3. The compound of claim 1 wherein Het is a bicyclic heteroaromatic ringcontaining from 1 to 3 nitrogens.
 4. The compound of claim 1 wherein R₁₅is nitro, lower alkyl sulfonyl, cyano, lower alkyl, lower alkoxy,perfluorolower alkyl, lower alkylthio, lower alkanoyl, or aryl.
 5. Thecompound of claim 4 wherein R₁₅ is unsubstituted phenyl.
 6. The compoundof claim 1 wherein R₁₆ is hydrogen, halogen, nitro, cyano, lower alkyl,perfluoro lower alkyl; and R₃₀ is hydrogen or lower alkyl.
 7. Thecompound of claim 1 wherein Het is a 6 membered monocyclicheteroaromatic ring containing 1 or 2 nitrogens or a 10 memberedbicyclic heteroaromatic ring containing one nitrogen, R₁₅ is loweralkyl, or perfluoroalkyl and R₁₆ is hydrogen, lower alkyl, orperfluoroalkyl, and R₃₀ is hydrogen.
 8. The compound of claim 1 whereinX-2 is selected from the group of


9. The compound of claim 1 wherein Y is

and X, R₂₂, R₂₃, and R₂₄ are as above.
 10. The compound of claim 9wherein R₂₂ and R₂₃ are lower alkyl, trifluoromethyl, or halogen and R₂₄is hydrogen, lower alkyl, lower alkoxy, or halogen.
 11. The compound ofclaim 10 wherein Y-1 is selected from the group of


12. The compound of claim 1 wherein Y is a group of the formula Y-2

and p, X, Het, R₃₀ and R₃₁, are as above.
 13. The compound of claim 12wherein Het is a 6 membered heteroaromatic ring.
 14. The compound ofclaim 13 wherein the heteroatom is N.
 15. The compound of claim 14wherein Y-2 is selected from the group of


16. The compound of claim 1 wherein Y is

and Y, R₂₅ and Q are as above, and the dotted bond can be optionallyhydrogenated.
 17. The compound of claim 16 wherein Y-3 is selected fromthe group of


18. The compound of claim 1 wherein R₅ is lower alkyl, nitro, halogen,or cyano and R₁₆ is hydrogen, lower alkyl, nitro, halogen,perfluorolower alkyl or cyano.
 19. The compound of claim 18 wherein Hetis pyridine or pyrimidine and R₁₅ is lower alkyl or perfluoroalkyl; andR₁₆ is hydrogen, lower alkyl, or perfluoroalkyl.
 20. The compound ofclaim 1 wherein Y is

where R₂₂ is hydrogen or lower alkyl, R₂₃ is halogen, lower alkyl, orperfluoroalkyl, and R₂₄ is hydrogen.
 21. The compound of claim 20wherein R₂₂ is hydrogen or methyl and R₂₃ is halogen, ethyl, ortrifluoromethyl.
 22. The compound of claim 1 wherein Y is a four to sixmembered cycloalkyl ring of formula

with R₂₅ being R₂₆—(CH₂)_(e)—, e is 2-4, and R₂₆ being alkoxy, loweralkyl sulfonyl, loweralkylthio, or NHR₂₉ where R₂₉ isloweralkoxycarbonyl or loweralkylaminocarbonyl, and the dotted bond ishydrogenated.
 23. The compound of claim 22 wherein R₂₆ is methoxy,methyl sulfonyl, or methylthio.
 24. The compound of claim 23 which is4-[(2,6-dimethyl-3-pyridinylcarbonyl)amino]-N-[[1-[(4-methylsulfonyl)butyl]cyclopentyl]thioxomethyl]-L-phenylalanine.25. The compound of claim 23 which is4-[[[4-(trifluoromethyl)-5-pyrimidinyl]carbonyl]amino]-N-[[1-(4-methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalanine.26. The compound of claim 23 which is4-[[(2,4-dimethyl-6-trifluoromethyl-3-pyridinyl)carbonyl]amino]-N-[[1-[(4-methylsulfonyl)butyl]cyclobutyl]thioxomethyl]-L-phenylalanine.